fix(server): close http listener cleanly on shutdown

src/main.py

@@ -288,7 +288,7 @@ async def main(port=80):
     def settings_page(request):
         """Serve the settings page."""
         return send_file('templates/settings.html')
-    
+
     # Favicon: avoid 404 in browser console (no file needed)
     @app.route('/favicon.ico')
     def favicon(request):
@@ -387,6 +387,17 @@ async def main(port=80):
                 )
             raise
     finally:
+        srv = getattr(app, "server", None)
+        if srv is not None:
+            try:
+                srv.close()
+                await srv.wait_closed()
+            except Exception:
+                pass
+            try:
+                app.server = None
+            except Exception:
+                pass
         if shutdown_handlers_registered:
             for sig in (signal.SIGINT, signal.SIGTERM):
                 try: