Add prebuild script to fetch event kinds from nostr library

- Add scripts/fetch-kinds.js to fetch kinds.json from central source
- Update package.json with prebuild hook to auto-fetch on build
- Regenerate eventKinds.js from https://git.mleku.dev/mleku/nostr/raw/branch/main/encoders/kind/kinds.json
- Now uses single source of truth for all 184 event kinds

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

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

app/web/package.json

@@ -4,6 +4,8 @@
   "private": true,
   "type": "module",
   "scripts": {
+    "fetch-kinds": "node scripts/fetch-kinds.js",
+    "prebuild": "npm run fetch-kinds",
     "build": "rollup -c",
     "dev": "rollup -c -w",
     "start": "sirv public --no-clear --single"