fix: restore EPG display in live TV player and channel cards

- Fix EPG not showing in NativePlayerScreen by reusing the shared
  mobileXtreamServiceProvider (cache already populated by channel cards)
  instead of creating a fresh service instance per player session
- Add periodic EPG refresh timer (every 5 min) matching LitePlayerScreen
- Fix empty-title fallback in _buildEPGBox
- Force dark theme, invert default live TV player (NativePlayer default),
  remove next-program display from OSD
- Fix back button exit dialog firing from wrong tab (add tab index guards)
- Halve card grid count for Movies/Series (6 categories, 8 items)
- Revamp Movies/Series search bars to match Live TV aesthetic
- Fix first channel row clipping when entering a category (scroll-to-top)
- Fix playlist edit dialog TV remote navigation
- Fix empty playlist screen button readability
- Remove theme switcher from settings

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/features/iptv/widgets/mobile_settings_tab.dart

@@ -117,10 +117,6 @@ class _MobileSettingsTabState extends ConsumerState<MobileSettingsTab> {
           // === APPARENCE ===
           _buildSectionHeader('Apparence'),
 
-          _buildThemeSwitcher(),
-
-          const SizedBox(height: 8),
-
           _buildSettingItem(
             icon: Icons.access_time,
             title: 'Afficher l\'heure',
@@ -360,8 +356,9 @@ class _MobileSettingsTabState extends ConsumerState<MobileSettingsTab> {
                         final selected = themeState.appThemeMode == mode;
                         final accentColor = Theme.of(context).colorScheme.primary;
                         return Expanded(
-                          child: GestureDetector(
-                            onTap: () => notifier.setThemeMode(mode),
+                          child: TVFocusable(
+                            onPressed: () => notifier.setThemeMode(mode),
+                            borderRadius: BorderRadius.circular(8),
                             child: AnimatedContainer(
                               duration: const Duration(milliseconds: 200),
                               margin: const EdgeInsets.symmetric(horizontal: 2),