Add global mini-player and improve configuration

- Add global activeRoom store for persistent WebSocket connection
- Add MiniPlayer component for playback controls across pages
- Add chunked S3 streaming with 64KB chunks and Range support
- Add queue item removal button
- Move DB credentials to environment variables
- Update .env.example with DB configuration

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

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

.env.example

@@ -1,3 +1,8 @@
+# Database
+DB_USER=postgres
+DB_PASSWORD=postgres
+DB_NAME=enigfm
+
 # JWT Secret (обязательно смените!)
 SECRET_KEY=your-secret-key-change-in-production