Fix NIP conformance in domain kinds; add domain docs/skill

docs/domain/content.md

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+# Content
+
+A grab-bag of content kinds: NIP-22 comments, NIP-7D forum threads, NIP-99 classifieds, NIP-52 calendar events, NIP-88 polls, and NIP-56 reports. Each is a plain `EventReader` / `EventBuilder` pair — see [Readers & Builders](./readers-and-builders) for the base pattern. The parameterized-replaceable kinds (`Classified`, `TimeEvent`) need a `d` tag (`setIdentifier()`).
+
+## Comment (kind 1111)
+
+NIP-22 comments distinguish the **thread root** (uppercase `E`/`A`/`K`/`P` tags) from the **immediate parent** (lowercase `e`/`a`/`k`/`p`). Both are read as a `CommentRef` (`{id?, address?, kind?, pubkey?}`).
+
+```typescript
+import {Comment, CommentBuilder} from "@welshman/domain"
+import type {CommentRef} from "@welshman/domain"
+
+const comment = await Comment.fromEvent(event)
+comment.root()     // CommentRef — uppercase tags (thread root)
+comment.parent()   // CommentRef — lowercase tags (immediate parent)
+
+// Set refs explicitly...
+const template = await new CommentBuilder()
+  .setContent("nice thread")
+  .setRoot(rootKind, rootId, rootPubkey)
+  .setParent(parentKind, parentId, parentPubkey)
+  .toTemplate()
+
+// ...or derive them from events (uses the event's d tag as identifier)
+await new CommentBuilder()
+  .setContent("reply")
+  .setRootFromEvent(rootEvent)
+  .setParentFromEvent(parentEvent)
+  .toEvent(signer)
+```
+
+::: warning Identifier quirk
+When you pass an `identifier` to `setRoot`/`setParent`, the builder pushes an `A`/`a` tag whose value is the `id` you passed — not a constructed `kind:pubkey:identifier` address. Be aware of this if you read those tags back expecting a full address.
+:::
+
+## Thread (kind 11)
+
+A NIP-7D forum thread root. Just a title plus the body content.
+
+```typescript
+import {Thread, ThreadBuilder} from "@welshman/domain"
+
+const thread = await Thread.fromEvent(event)
+thread.title()     // "title" tag value
+
+await new ThreadBuilder()
+  .setTitle("Welcome")
+  .setContent("Read the rules first.")
+  .toEvent(signer)
+```
+
+## Classified (kind 30402)
+
+A NIP-99 marketplace listing. The price parses into a `ClassifiedPrice` (`{amount, currency, frequency}`), defaulting currency to `SAT`.
+
+```typescript
+import {Classified, ClassifiedBuilder} from "@welshman/domain"
+import type {ClassifiedPrice} from "@welshman/domain"
+
+const listing = await Classified.fromEvent(event)
+listing.title()     // "title" tag value
+listing.summary()   // "summary" tag value
+listing.price()     // ClassifiedPrice | undefined
+listing.status()    // "status" tag value
+listing.images()    // "image" tag values
+listing.topics()    // t-tag values
+
+await new ClassifiedBuilder()
+  .setIdentifier()                       // required d tag for kind 30402
+  .setTitle("Bike for sale")
+  .setSummary("lightly used")
+  .setPrice(150, "USD", "")              // amount, currency = "SAT", frequency = ""
+  .setStatus("active")
+  .setImages(["https://example.com/bike.jpg"])
+  .setTopics(["bikes", "forsale"])
+  .toEvent(signer)
+```
+
+## TimeEvent (kind 31923)
+
+A NIP-52 time-based calendar event.
+
+```typescript
+import {TimeEvent, TimeEventBuilder} from "@welshman/domain"
+
+const evt = await TimeEvent.fromEvent(event)
+evt.title()      // "title" tag value
+evt.location()   // "location" tag value
+evt.start()      // unix seconds as int, or undefined
+evt.end()        // unix seconds as int, or undefined
+
+await new TimeEventBuilder()
+  .setIdentifier()                       // required d tag for kind 31923
+  .setTitle("Nostrica")
+  .setLocation("Costa Rica")
+  .setStart(startTs)
+  .setEnd(endTs)
+  .toEvent(signer)
+```
+
+When both `start` and `end` are set, `buildTags` auto-generates one `["D", dayIndex]` tag per day in `[start, end)` (day-bucket index tags), so the event is discoverable by day.
+
+## Poll (kind 1068) and PollResponse (kind 1018)
+
+NIP-88 polls. A `Poll` has a title (content), options, a type, and an optional close time. Types are exported as `PollType` (`"singlechoice" | "multiplechoice"`), options as `PollOption`, and tallies as `PollResult`.
+
+```typescript
+import {Poll, PollBuilder} from "@welshman/domain"
+import type {PollType, PollOption, PollResult} from "@welshman/domain"
+
+const poll = await Poll.fromEvent(event)
+poll.title()        // event.content (or "")
+poll.options()      // PollOption[] — {id, label}
+poll.pollType()     // PollType, default "singlechoice"
+poll.endsAt()       // unix seconds | undefined
+poll.isClosed()     // boolean (endsAt <= now)
+poll.urls()         // "relay" tag values
+
+await new PollBuilder()
+  .setTitle("Favorite client?")
+  .addOption("Coracle")              // id defaults to a random id
+  .addOption("Flotilla")
+  .setPollType("singlechoice")
+  .setEndsAt(closeTs)
+  .toEvent(signer)
+```
+
+`validate()` requires at least one option. To tally votes, pass the response events to `results`:
+
+```typescript
+const result: PollResult = poll.results(responseEvents)
+result.options   // [{id, label, votes}, …]
+result.voters    // number of distinct voters
+```
+
+`results` keeps only each pubkey's latest response, takes the first selection for single-choice polls, and the unique selections for multiple-choice.
+
+A `PollResponse` is one voter's answer:
+
+```typescript
+import {PollResponse, PollResponseBuilder} from "@welshman/domain"
+
+const response = await PollResponse.fromEvent(event)
+response.pollId()       // e-tag value
+response.selections()   // unique "response" tag values
+
+await new PollResponseBuilder()
+  .setPollId(pollId)
+  .addSelection(optionId)     // deduped
+  .toEvent(signer)
+```
+
+`PollResponse.validate()` requires a pollId.
+
+## Report (kind 1984)
+
+A NIP-56 report flags a pubkey and/or an event with a reason.
+
+```typescript
+import {Report, ReportBuilder} from "@welshman/domain"
+
+const report = await Report.fromEvent(event)
+report.reportedPubkey()   // p-tag value
+report.eventId()          // e-tag value (tag[1])
+report.reason()           // e-tag reason (tag[2])
+
+await new ReportBuilder()
+  .setReportedPubkey(pubkey)
+  .setEventId(noteId)
+  .setReason("spam")
+  .toEvent(signer)
+```
+
+`buildTags` emits `["p", pubkey]` and `["e", id, reason?]`.
+
+## See also
+
+- [Readers & Builders](./readers-and-builders) — the base `EventReader`/`EventBuilder` pattern, including `d`-tag validation for `Classified` and `TimeEvent`.