fix(ci): exclude bin/ from root analyzer and clean remaining warnings

The frontend CI job ran `flutter analyze` from the repo root, which also
analyzed the bin/ server package without its dependencies resolved
(shelf_router, sqlite3, bcrypt, test), producing hundreds of
uri_does_not_exist errors. bin/ is a standalone package covered by the
backend job, so it is now excluded from root analysis.

Also:
- Remove all unused fields/variables flagged as analyzer warnings
  (api_client, cache_service, player_screen, subtitle_service,
  live_tv_tab, mobile screens)
- Run `flutter analyze --no-fatal-infos` in CI: pre-existing deprecation
  infos (withOpacity, dart:html) stay non-fatal while errors and warnings
  still fail the build

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/mobile/features/iptv/widgets/mobile_settings_tab.dart

@@ -62,7 +62,6 @@ class _MobileSettingsTabState extends ConsumerState<MobileSettingsTab> {
   Widget build(BuildContext context) {
     final currentUser = ref.watch(authProvider).currentUser;
     final settings = ref.watch(iptvSettingsProvider);
-    final themeState = ref.watch(themeProvider);
     final themeNotifier = ref.read(themeProvider.notifier);
     final isDark = Theme.of(context).brightness == Brightness.dark;