Add WebSocket support for real-time media status updates

Replace HTTP polling with WebSocket push notifications for instant
state change responses. Server broadcasts updates only when significant
changes occur (state, track, volume, etc.) while letting Home Assistant
interpolate position during playback. Includes seek detection for
timeline updates and automatic fallback to HTTP polling if WebSocket
disconnects.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

media_server/main.py

@@ -11,6 +11,8 @@ from fastapi.middleware.cors import CORSMiddleware
 
 from .config import settings, generate_default_config, get_config_dir
 from .routes import health_router, media_router, scripts_router
+from .services import get_media_controller
+from .services.websocket_manager import ws_manager
 
 
 def setup_logging():
@@ -29,7 +31,16 @@ async def lifespan(app: FastAPI):
     logger = logging.getLogger(__name__)
     logger.info(f"Media Server starting on {settings.host}:{settings.port}")
     logger.info(f"API Token: {settings.api_token[:8]}...")
+
+    # Start WebSocket status monitor
+    controller = get_media_controller()
+    await ws_manager.start_status_monitor(controller.get_status)
+    logger.info("WebSocket status monitor started")
+
     yield
+
+    # Stop WebSocket status monitor
+    await ws_manager.stop_status_monitor()
     logger.info("Media Server shutting down")