feat: skeleton loaders, Sentry source maps, auto-deploy via webhook

RoomSkeleton: shimmer skeleton matching Room header/timeline/input layout,
  used as Suspense fallback for all three Room routes (home/direct/space)

Sentry source maps: @sentry/vite-plugin uploads 72 hidden source map files
  to Sentry on each build then deletes them from dist — stack traces now show
  real file/line numbers instead of minified bundle positions.
  Auth token loaded from /etc/lotus-deploy.env (not in git).

Auto-deploy: webhook receiver on port 9001, nginx proxies
  /hooks/lotus-deploy, HMAC-SHA256 verified, triggers on lotus branch push.
  Deploy script: git reset --hard + npm ci + npm run build + rsync to webroot.

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

package.json

@@ -128,6 +128,7 @@
     "@rollup/plugin-wasm": "6.1.1",
     "@semantic-release/exec": "7.1.0",
     "@semantic-release/git": "10.0.1",
+    "@sentry/vite-plugin": "5.3.0",
     "@types/chroma-js": "3.1.1",
     "@types/file-saver": "2.0.5",
     "@types/is-hotkey": "0.1.10",