Bootstrap project, add protocol

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+NIP-XX
+======
+
+FROST Multisig Quorum Protocol
+-------------------------------
+
+`draft` `optional`
+
+## Abstract
+
+This NIP defines a protocol for creating and operating FROST threshold signature quorums over Nostr keys. A quorum is a group of n participants who collectively control a shared Nostr keypair via a (t,n) threshold signing scheme, where any t members can produce a valid signature but no fewer. The quorum's private key is never known to any single party.
+
+## Participant Indexing
+
+Each member is assigned a positive integer index. Indices are derived deterministically by sorting member pubkeys lexicographically as lowercase hex strings and assigning 1-based positions. This ordering must be consistent across all participants and all rounds of a session.
+
+When a new member set is established (rotation), indices are re-derived from the new member list.
+
+## Event Kinds
+
+All events in this protocol are sent as the `content` payload of a NIP-59 gift wrap (kind 1059). The `content` is encrypted to the recipient's pubkey and the wrap is sent to the recipients inbox relays (kind 10050) per NIP 17.
+
+## Quorum Creation
+
+Creates a new quorum and derives its shared Nostr keypair. The private key is never known to any party.
+
+### Phase 0 — Invitation (kind 7050)
+
+The initiator sends each proposed member a gift-wrapped event:
+
+```json
+{
+  "kind": 7050,
+  "content": "<optional human-readable message>",
+  "tags": [
+    ["session_id", "<32-byte random hex>"],
+    ["threshold", "<signing threshold>"],
+    ["member", "<pk_1>"],
+    ["member", "<pk_n>"],
+  ],
+}
+```
+
+`session_id` is chosen by the initiator and identifies all subsequent events for this DKG session. The quorum's keypair does not yet exist; no key material is present in the invite.
+
+Participation in Round 1 signals acceptance. A member may send a decline event, but is not required to.
+
+### Round 1 — Commitments (kind 7051)
+
+Each accepting participant Pᵢ:
+
+1. Samples a random polynomial `fᵢ(x)` of degree `t−1` over the secp256k1 scalar field, with random coefficients `aᵢ₀, aᵢ₁, …, aᵢ,ₜ₋₁`
+2. Computes Feldman commitments: `Cᵢ = [aᵢ₀·G, aᵢ₁·G, …, aᵢ,ₜ₋₁·G]` (compressed 33-byte EC points as hex)
+3. Computes a Schnorr proof of knowledge of `aᵢ₀`:
+   - Sample ephemeral scalar `k`; compute `R = k·G`
+   - `c = H("frost/dkg/round1" || session_id || pkᵢ || Cᵢ[0])`
+   - `s = k + aᵢ₀ · c  (mod q)`
+4. Sends to all other members (n−1 gift wraps, identical payload):
+
+```json
+{
+  "kind": 7051,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["commit", "<aᵢ₀·G hex>"],
+    ["commit", "<aᵢ₁·G hex>"],
+    ["proof", "<R hex>", "<s hex>"]
+  ]
+}
+```
+
+### Round 2 — Share Distribution (kind 7052)
+
+After receiving Round 1 from all other participants, Pᵢ:
+
+1. Verifies each Pⱼ's PoK: `s·G == R + c·Cⱼ[0]` where `c` is recomputed from the proof
+2. For each Pⱼ (j ≠ i), evaluates `sᵢⱼ = fᵢ(j)` (polynomial evaluated at Pⱼ's 1-based index)
+3. Sends encrypted to Pⱼ only (one gift wrap per recipient):
+
+```json
+{
+  "kind": 7052,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["share", "<sᵢⱼ hex scalar>"]
+  ]
+}
+```
+
+### Finalization
+
+Each Pⱼ, after receiving shares from all other participants:
+
+1. Verifies each received share against Pᵢ's commitments:
+
+   `sᵢⱼ·G == Σₖ₌₀ᵗ⁻¹ ( j^k · Cᵢₖ )`
+
+   Abort if any check fails.
+
+2. Computes secret shard: `xⱼ = Σᵢ sᵢⱼ  (mod q)`
+
+3. Computes group public key: `Y = Σᵢ Cᵢ₀` (sum of all participants' first commitments)
+
+4. Computes own verification share: `Yⱼ = Σᵢ Σₖ₌₀ᵗ⁻¹ ( j^k · Cᵢₖ )`; verify `xⱼ·G == Yⱼ`
+
+5. **BIP-340 normalization**: if `Y` has odd y-coordinate, negate `xⱼ` and `Yⱼ` and use the even-y form of `Y` as the quorum pubkey. This negation must be applied consistently across all subsequent operations.
+
+6. Stores `(xⱼ, Y, Yⱼ, members, threshold, session_id, Round-1 commitments)` durably in IndexedDB. The Round-1 commitments are retained because they are needed to verify resharing participants' shards in Protocol 2.
+
+7. Publishes a DKG confirmation event (kind 7053).
+
+### Confirmation (kind 7053)
+
+```json
+{
+  "kind": 7053,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["transcript", "<H(session_id || sorted Round-1 commitments)>"]
+  ]
+}
+```
+
+`transcript_hash` enables equivocation detection: a malicious participant may send different Round-1 commitments to different members. If any two confirmations carry the same `session_id` but different `transcript_hash` or `quorum_pubkey`, all participants must abort.
+
+The quorum is considered live once `t` confirmations with matching `transcript_hash` and `quorum_pubkey` have been observed.
+
+---
+
+## Protocol 2: Key Redistribution (Rotation)
+
+Redistributes the existing quorum key to a new member set and/or threshold without reconstructing the private key. The quorum's Nostr pubkey `Y` is preserved, so the quorum's identity, profile, and event history are unaffected.
+
+**Prerequisite**: A contributing set `S` of at least `t` current members must participate.
+
+### Phase 0 — Resharing Proposal (kind 7054)
+
+The initiator (a current member) sends to all current and prospective new members:
+
+```json
+{
+  "kind": 7054,
+  "content": "<optional human-readable message>",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["threshold", "<t'>"],
+    ["old_member", "<pk_1>"],
+    ["old_member", "<pk_n>"],
+    ["member", "<pk_1'>"],
+    ["member", "<pk_n'>"]
+  ]
+}
+```
+
+New member indices are derived by sorting `new_members` lexicographically (1-based), independently of the old index assignment.
+
+Old members signal participation by contributing in Round 1. The contributing set `S` **must be fixed before shares are combined**, because each old member's Lagrange coefficient depends on the full set `S`. Implementations should establish `S` via a timeout or an explicit "I'm participating" acknowledgment step before proceeding to Round 2.
+
+### Round 1 — Old Member Commitments (kind 7055)
+
+Each participating old member Pᵢ (with index `i` from the original DKG and shard `xᵢ`):
+
+1. Computes Lagrange coefficient over contributing set `S` at point 0:
+
+   `λᵢ = Πⱼ∈S, j≠i  (-j) / (i - j)  (mod q)`
+
+2. Samples a new random polynomial `hᵢ(x)` of degree `t'−1` with constant term `hᵢ(0) = λᵢ · xᵢ`
+
+3. Computes commitments: `Dᵢ = [λᵢ·xᵢ·G, …]` (same structure as Round-1 commitments in Protocol 1)
+
+4. The first commitment `Dᵢ[0]` must equal `λᵢ · Yᵢ`, where `Yᵢ` is Pᵢ's verification share from the original DKG (publicly computable from stored Round-1 commitments). This proves Pᵢ is resharing their actual shard.
+
+5. Computes Schnorr PoK of `λᵢ · xᵢ` (same construction as Protocol 1 Round 1, using `"frost/resharing/round1"` as domain tag)
+
+6. Sends to all new members (m gift wraps, identical payload):
+
+```json
+{
+  "kind": 7055,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["commit", "<λᵢ·xᵢ·G hex>"],
+    ["commit", "<bᵢ₁·G hex>"],
+    ["proof", "<R hex>", "<s hex>"]
+  ]
+}
+```
+
+New members verify before proceeding: `Σᵢ∈S Dᵢ[0] == Y`. Abort if this check fails.
+
+### Round 2 — Share Distribution (kind 7056)
+
+Each participating old member Pᵢ evaluates `hᵢ(j)` at each new member Qⱼ's index `j` and sends encrypted to Qⱼ only:
+
+```json
+{
+  "kind": 7056,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["share", "<hᵢ(j) hex scalar>"]
+  ]
+}
+```
+
+### Finalization
+
+Each new member Qⱼ, after receiving shares from all members of `S`:
+
+1. Verifies each received share against Dᵢ commitments:
+
+   `hᵢ(j)·G == Σₖ₌₀ᵗ'⁻¹ ( j^k · Dᵢₖ )`
+
+   Abort if any check fails.
+
+2. Computes new shard: `x'ⱼ = Σᵢ∈S hᵢ(j)  (mod q)`
+
+3. Computes new verification share: `Y'ⱼ = Σᵢ∈S Σₖ ( j^k · Dᵢₖ )`; verify `x'ⱼ·G == Y'ⱼ`
+
+4. BIP-340 normalization: `Y` is unchanged, so the same even-y convention applies. If `xᵢ` was negated during the original DKG finalization, `hᵢ(0) = λᵢ · xᵢ` already incorporates that negation. Qⱼ verifies against the same `Y` and does not re-negate.
+
+5. Replaces stored quorum state with `(x'ⱼ, Y, Y'ⱼ, new_members, new_threshold, session_id, Round-1 commitments from this session)`.
+
+6. Publishes resharing confirmation (kind 7057).
+
+### Resharing Confirmation (kind 7057)
+
+```json
+{
+  "kind": 7057,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["transcript", "<H(session_id || sorted Round-1 commitments)>"]
+  ]
+}
+```
+
+Once `t'` new members have published matching confirmations, the rotation is considered complete. The quorum then publishes a signed `kind 0` metadata event under `Y` recording the new member list. This event is the on-chain rotation record and is used to gate NIP-17 chat display by membership at time of message.
+
+---
+
+## Protocol 3: Collaborative Signing (FROST)
+
+Any quorum member may initiate a signing session. At least t members must participate to produce a valid signature.
+
+### Sign Request (kind 7058)
+
+The initiator sends to all members:
+
+```json
+{
+  "kind": 7058,
+  "content": "<JSON-stringified unsigned nostr event>",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"]
+  ]
+}
+```
+
+### Round 1 — Nonce Commitments (kind 7059)
+
+Each willing signer Pᵢ:
+
+1. Samples ephemeral nonce pair `(dᵢ, eᵢ)` uniformly at random (must never be reused)
+2. Computes commitments `Dᵢ = dᵢ·G`, `Eᵢ = eᵢ·G`
+3. Sends to all other participating signers:
+
+```json
+{
+  "kind": 7059,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["D", "<dᵢ·G hex>"],
+    ["E", "<eᵢ·G hex>"]
+  ]
+}
+```
+
+### Round 2 — Signature Shares (kind 7060)
+
+After collecting Round 1 from at least `t` signers, each Pᵢ:
+
+1. Finalizes the signing set `S` (the participants whose commitments were collected)
+2. Computes binding factors: `ρᵢ = H("frost/sign/rho" || i || msg || {(Dⱼ, Eⱼ)}ⱼ∈S)` for each `i ∈ S`
+3. Computes group nonce: `R = Σᵢ∈S (Dᵢ + ρᵢ·Eᵢ)`; if `R` has odd y-coordinate, negate `dᵢ, eᵢ` and use the even-y `R`
+4. Computes BIP-340 challenge: `c = H_BIP340("BIP0340/challenge" || R.x || Y || msg)`
+5. Computes Lagrange coefficient `λᵢ` over `S` at point 0 (same formula as Protocol 2)
+6. Computes signature share: `zᵢ = dᵢ + eᵢ·ρᵢ + λᵢ·xᵢ·c  (mod q)` (using the BIP-340-normalized `xᵢ`)
+7. Sends to coordinator:
+
+```json
+{
+  "kind": 7060,
+  "content": "",
+  "tags": [
+    ["session_id", "<32-byte hex>"],
+    ["quorum", "<Y x-only hex>"],
+    ["z", "<zᵢ hex scalar>"]
+  ]
+}
+```
+
+### Aggregation
+
+The coordinator (any member) aggregates:
+
+- `z = Σᵢ∈S zᵢ  (mod q)`
+- Final signature: `(R.x, z)`
+
+The coordinator verifies the signature against `Y` and `msg` using standard BIP-340 verification before publishing the event. The resulting signature is a valid BIP-340 Schnorr signature, indistinguishable from a single-key signature.
+
+---
+
+## Storage
+
+Quorum state must be stored durably in IndexedDB per-quorum:
+
+| Field | Description |
+|-------|-------------|
+| `quorum_pubkey` | `Y` as x-only hex — the quorum's Nostr pubkey |
+| `shard` | `xⱼ` — this member's secret share (encrypted at rest) |
+| `verification_share` | `Yⱼ` — public verification share for this member |
+| `members` | Current member pubkeys and indices |
+| `threshold` | Current signing threshold `t` |
+| `dkg_commitments` | All participants' Round-1 commitments from the most recent DKG or resharing session |
+| `rotation_records` | All signed rotation `kind 0` events in order |
+
+`dkg_commitments` are retained permanently because they are required to verify shard authenticity during resharing (step 4 of Protocol 2 Round 1).
+
+`rotation_records` are used to determine which members were active at a given time, which gates NIP-17 chat message display.
+
+---
+
+## Security Notes
+
+**Equivocation**: A malicious participant can send different Round-1 commitments to different members, causing different members to derive different group keys. The `transcript_hash` in confirmation events provides detection. Implementations must abort if any two confirmations for the same session have different hashes.
+
+**Abort and restart**: If any participant fails to complete their round within a timeout, the session must be fully aborted. Partial state (nonces, sub-shares) must be discarded. A new session with a new `session_id` must be started from Phase 0.
+
+**Nonce reuse in signing**: Reusing `(dᵢ, eᵢ)` across two signing sessions leaks the shard `xᵢ`. Implementations must use fresh randomness for every session and must not persist signing nonces.
+
+**Contributing set integrity**: In Protocol 2, the Lagrange coefficients and the integrity check `Σ Dᵢ[0] == Y` are only meaningful over the same set `S`. The set must be fixed and agreed upon before shares are combined. Any late-joining or aborting member after `S` is finalized requires a full session restart.
+
+**BIP-340 y-coordinate normalization**: Nostr uses x-only public keys. Both the group key `Y` (finalized in DKG) and the signing nonce `R` (per signing session) require even-y normalization, which affects the sign of `xⱼ` and `(dᵢ, eᵢ)` respectively. These negations are independent and must both be applied correctly.