Update development scripts and add macOS icon assets

- Renamed backend development script from `dev:backend` to `dev:server` for clarity.
- Added new macOS icon assets and configuration files for the application.
- Enhanced App component to improve server management during production and development modes.
- Updated ConnectionForm to reset state after successful submission and conditionally render the update button.
- Implemented database initialization on application startup in the backend.

backend/main.py

@@ -706,6 +706,7 @@ async def trigger_model_download(request: models.ModelDownloadRequest):
 async def startup_event():
     """Run on application startup."""
     print("voicebox API starting up...")
+    database.init_db()
     print(f"Database initialized at {database._db_path}")
     print(f"GPU available: {torch.cuda.is_available()}")