style: apply analyzer lint fixes across lib

Initializing formals, unawaited() on fire-and-forget futures, unused
import removal, wildcard params, and mounted vs context.mounted.

lib/screens/livetv/tabs/guide_tab.dart

@@ -1112,7 +1112,7 @@ class GuideTabState extends State<GuideTab> with MountedSetStateMixin, WidgetsBi
       _gridEnd = _gridStart.add(const Duration(hours: 6));
       _nowWasInWindow = _nowInWindow(DateTime.now());
     });
-    _loadPrograms();
+    unawaited(_loadPrograms());
     _guideFocusNode.requestFocus();
   }