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/features/iptv/services/subtitle_service.dart

@@ -42,9 +42,6 @@ class SubtitleEntry {
 
 /// Service for handling subtitles
 class SubtitleService {
-  static const _srtPattern =
-      r'(\d+)\n(\d{2}):(\d{2}):(\d{2}),(\d{3}) --> (\d{2}):(\d{2}):(\d{2}),(\d{3})\n([\s\S]*?)(?=\n\n|\Z)';
-
   /// Parse SRT subtitle content
   static List<SubtitleEntry> parseSrt(String content) {
     final entries = <SubtitleEntry>[];