fix: bundle UI dist into server package for npm publishing

The server's static-ui mode resolves the UI dist path relative to its
own directory. In the monorepo it finds ../../ui/dist, but when published
to npm the UI package isn't available.

- server/src/app.ts: try ../ui-dist (published) then ../../ui/dist (dev),
  gracefully degrade to API-only if neither exists
- server/package.json: include ui-dist/ in published files
- scripts/release.sh: build UI and copy dist to server/ui-dist before
  publishing, clean up in restore step

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/package.json

@@ -17,7 +17,8 @@
     "types": "./dist/index.d.ts"
   },
   "files": [
-    "dist"
+    "dist",
+    "ui-dist"
   ],
   "scripts": {
     "dev": "tsx src/index.ts",