fix: Docker one-click deployment — all deps bundled, native modules, health check

- Multi-stage build: builder installs backend + frontend deps, compiles
- Production stage: npm ci --production rebuilds native modules (opus, sqlite3)
- FFmpeg bundled via ffmpeg-static (no apt install ffmpeg)
- .dockerignore prevents node_modules/dist from being copied
- docker-compose uses host network for TS3 UDP connectivity
- Named volume for persistent data
- Health check endpoint

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,13 @@
+node_modules/
+web/node_modules/
+dist/
+web/dist/
+data/
+*.db
+.env
+config.json
+cookies/
+.git/
+.claude/
+docs/superpowers/
+test-*.ts