Add secure nsec key generation and encryption for web UI (v0.36.7)

- Add nsec-crypto.js library with Argon2id+AES-GCM encryption
- Generate new nsec keys using secure system entropy
- Encrypt nsec with password (~3 sec Argon2id derivation in Web Worker)
- Add unlock flow for returning users with encrypted keys
- Add deriving modal with live timer during key derivation
- Auto-create default profile for new users with ORLY logo avatar
- Fix NIP-42 auth race condition in websocket-auth.js
- Improve header user profile display (avatar fills height, no truncation)
- Add instant light/dark theme colors in HTML head
- Add background box around username/nip05 in settings drawer
- Update CLAUDE.md with nsec-crypto library documentation

Files modified:
- app/web/src/nsec-crypto.js: New encryption library
- app/web/src/LoginModal.svelte: Key gen, encryption, unlock UI
- app/web/src/nostr.js: Default profile creation
- app/web/src/App.svelte: Header and drawer styling
- app/web/public/index.html: Instant theme colors
- CLAUDE.md: Library documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/web/bun.lock

@@ -6,6 +6,7 @@
       "dependencies": {
         "applesauce-core": "^4.4.2",
         "applesauce-signers": "^4.2.0",
+        "hash-wasm": "^4.12.0",
         "nostr-tools": "^2.17.0",
         "sirv-cli": "^2.0.0",
       },
@@ -143,6 +144,8 @@
 
     "hash-sum": ["hash-sum@2.0.0", "", {}, "sha512-WdZTbAByD+pHfl/g9QSsBIIwy8IT+EsPiKDs0KNX+zSHhdDLFKdZu0BQHljvO+0QI/BasbMSUa8wYNCZTvhslg=="],
 
+    "hash-wasm": ["hash-wasm@4.12.0", "", {}, "sha512-+/2B2rYLb48I/evdOIhP+K/DD2ca2fgBjp6O+GBEnCDk2e4rpeXIK8GvIyRPjTezgmWn9gmKwkQjjx6BtqDHVQ=="],
+
     "hasown": ["hasown@2.0.2", "", { "dependencies": { "function-bind": "^1.1.2" } }, "sha512-0hJU9SCPvmMzIBdZFqNPXWa6dqh7WdH0cII9y+CyS8rG3nL48Bclra9HmKhVVUHyPWNH5Y7xDwAB7bfgSjkUMQ=="],
 
     "ignore": ["ignore@5.3.2", "", {}, "sha512-hsBTNUqQTDwkWtcdYI2i06Y/nUBEsNEDJKjWdigLvegy8kDuJAS8uRlpkkcQpyEXL0Z/pjDy5HBmMjRCJ2gq+g=="],