Add docs for blossom, add nip 86 and 98 support

docs/util/blossom.md

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+# Blossom
+
+Client library for interacting with Blossom media servers. Provides utilities for authentication, blob operations, and file encryption.
+
+## Types
+
+```typescript
+export type BlossomAuthAction = "get" | "upload" | "list" | "delete"
+
+export type BlossomAuthEventOpts = {
+  action: BlossomAuthAction
+  server: string
+  hashes?: string[]
+  expiration?: number
+  content?: string
+}
+
+export type BlossomServer = {
+  url: string
+  pubkey?: string
+}
+
+export type BlossomErrorResponse = {
+  message: string
+  reason?: string
+}
+
+export interface EncryptedFile {
+  key: string
+  nonce: string
+  ciphertext: Uint8Array
+  algorithm: string
+}
+```
+
+## Authentication
+
+```typescript
+// Creates a Blossom auth event for server operations
+export declare const makeBlossomAuthEvent: (opts: BlossomAuthEventOpts) => Event
+```
+
+## Blob Operations
+
+```typescript
+// Builds URL for accessing a blob
+export declare const buildBlobUrl: (server: string, sha256: string, extension?: string) => string
+
+// Checks if a blob exists on server
+export declare const checkBlobExists: (server: string, sha256: string, options?: { authEvent?: SignedEvent }) => Promise<{exists: boolean; size?: number}>
+
+// Downloads blob from server
+export declare const getBlob: (server: string, sha256: string, options?: { authEvent?: SignedEvent; range?: {start: number; end?: number} }) => Promise<Response>
+
+// Uploads blob to server
+export declare const uploadBlob: (server: string, blob: Blob | ArrayBuffer, options?: { authEvent?: SignedEvent }) => Promise<Response>
+
+// Deletes blob from server
+export declare const deleteBlob: (server: string, sha256: string, options?: { authEvent?: SignedEvent }) => Promise<Response>
+
+// Lists blobs for a pubkey
+export declare const listBlobs: (server: string, pubkey: string, options?: { authEvent?: SignedEvent; since?: number; until?: number }) => Promise<Response>
+```
+
+## File Encryption
+
+```typescript
+// Encrypts a file using AES-GCM
+export declare function encryptFile(file: Blob): Promise<EncryptedFile>
+
+// Decrypts an encrypted file
+export declare function decryptFile(encryptedFile: EncryptedFile): Promise<Uint8Array>
+```
+
+## Example
+
+```typescript
+import { uploadBlob, makeBlossomAuthEvent } from '@welshman/util'
+
+// Create auth event for upload
+const authEvent = makeBlossomAuthEvent({
+  action: "upload",
+  server: "https://blossom.example.com"
+})
+
+// Sign the auth event with your signer
+const signedAuthEvent = await signer.signEvent(authEvent)
+
+// Upload a file
+const file = new File(["Hello world"], "hello.txt", { type: "text/plain" })
+const response = await uploadBlob("https://blossom.example.com", file, {
+  authEvent: signedAuthEvent
+})
+```