feat: extend Force TV mode to desktop for home-theater setups

Initialize TvDetectionService on every platform so the existing
force_tv_mode setting drives the 10-foot TV interface on Windows,
macOS, and Linux, and surface the toggle in appearance settings there.

Desktop keeps real-mouse behavior in TV mode: InputModeTracker still
flips between pointer and keyboard modes (cursor hidden while
keyboard-driven), segmented controls keep their hover affordance, and
the settings backup section stays available (only Android TV lacks a
document picker).

Adds PlatformDetector.debugSetIsDesktopOSOverride so TV-device
simulations in widget tests don't inherit the desktop test host's
platform.

close #1409

lib/focus/input_mode_tracker.dart

@@ -117,8 +117,10 @@ class _InputModeTrackerState extends State<InputModeTracker> {
   Widget build(BuildContext context) {
     // On Android TV, don't switch to pointer mode from pointer events
     // as D-pad can generate synthetic pointer events that would incorrectly
-    // trigger pointer mode and show a cursor instead of D-pad focus navigation
+    // trigger pointer mode and show a cursor instead of D-pad focus navigation.
-    if (TvDetectionService.isTVSync()) {
+    // Desktop is exempt even in force-TV mode: its pointer events come from a
+    // real mouse, which should keep flipping modes (and the cursor) as usual.
+    if (TvDetectionService.isTVSync() && !PlatformDetector.isDesktopOS()) {
       return _InputModeProvider(mode: _mode, child: widget.child);
     }
 

lib/main.dart

@@ -179,10 +179,10 @@ Future<void> _bootstrapApp() async {
     }
   }
 
-  // Initialize TV detection (Android leanback or Apple TV) and PiP on Android.
+  // Initialize TV detection on every platform: auto-detect covers Android
-  if (Platform.isAndroid || Platform.isIOS) {
+  // leanback and Apple TV; the force-TV setting applies anywhere, including
-    futures.add(TvDetectionService.getInstance(forceTv: settings.read(SettingsService.forceTvMode)));
+  // desktop home-theater setups.
-  }
+  futures.add(TvDetectionService.getInstance(forceTv: settings.read(SettingsService.forceTvMode)));
   // Visual-effects tier (auto-detects low-end Android; full elsewhere).
   futures.add(DevicePerformance.getInstance(override: settings.read(SettingsService.visualEffects)));
   if (Platform.isAndroid) {

lib/screens/settings/appearance_settings_screen.dart

@@ -102,7 +102,7 @@ class AppearanceSettingsScreen extends StatelessWidget {
           title: t.settings.navigation,
           children: [
             _startupSectionSelector(),
-            if (Platform.isAndroid)
+            if (Platform.isAndroid || PlatformDetector.isDesktopOS())
               SettingSwitchTile(
                 pref: SettingsService.forceTvMode,
                 icon: Symbols.tv_rounded,

lib/screens/settings/settings_screen.dart

@@ -164,7 +164,9 @@ class _SettingsScreenState extends State<SettingsScreen> with FocusableTab, Moun
 
                 if (UpdateService.isUpdateCheckEnabled) ...[_buildUpdateSection()],
 
-                if (!PlatformDetector.isTV()) _buildBackupSection(),
+                // Hidden on Android TV / tvOS (no document picker); desktop in
+                // force-TV mode keeps it — FilePickerService works there.
+                if (!PlatformDetector.isTV() || PlatformDetector.isDesktopOS()) _buildBackupSection(),
 
                 const SizedBox(height: 24),
                 SettingsGroup(

lib/utils/platform_detector.dart

@@ -202,7 +202,16 @@ class PlatformDetector {
   /// BuildContext. Use for OS-level capability checks (window state, native
   /// keyboard, etc.); use [isDesktop] for layout decisions.
   static bool isDesktopOS() {
-    return Platform.isWindows || Platform.isMacOS || Platform.isLinux;
+    return _debugIsDesktopOSOverride ?? (Platform.isWindows || Platform.isMacOS || Platform.isLinux);
+  }
+
+  static bool? _debugIsDesktopOSOverride;
+
+  /// Test-only: override [isDesktopOS] so device simulations (Android TV /
+  /// Apple TV) don't inherit the test host's real platform.
+  @visibleForTesting
+  static void debugSetIsDesktopOSOverride(bool? value) {
+    _debugIsDesktopOSOverride = value;
   }
 
   static bool supportsExternalPlayers() {

lib/widgets/expressive_button_group.dart

@@ -210,8 +210,9 @@ class _ExpressiveButtonGroupState<T> extends State<ExpressiveButtonGroup<T>> {
         onTap: () => _commit(segment),
         child: child,
       );
-      // Hover tracking + click cursor; skipped on TV like ClickableCursor.
+      // Hover tracking + click cursor; skipped on TV like ClickableCursor,
-      if (!PlatformDetector.isTV()) {
+      // except on desktop (force-TV mode there still has a real mouse).
+      if (!PlatformDetector.isTV() || PlatformDetector.isDesktopOS()) {
         child = MouseRegion(
           cursor: SystemMouseCursors.click,
           onEnter: (_) => setState(() => _hoveredIndex = i),

test/screens/profile/add_local_profile_screen_test.dart

@@ -14,12 +14,16 @@ void main() {
   setUp(() {
     resetSharedPreferencesForTest();
     TvDetectionService.debugSetAppleTVOverride(true);
+    // Simulated TV device: the test host's desktop OS must not leak into
+    // InputModeTracker's desktop force-TV exemption.
+    PlatformDetector.debugSetIsDesktopOSOverride(false);
     LocaleSettings.setLocaleSync(AppLocale.en);
   });
 
   tearDown(() {
     TvDetectionService.debugSetAppleTVOverride(null);
     TvDetectionService.setForceTVSync(false);
+    PlatformDetector.debugSetIsDesktopOSOverride(null);
   });
 
   testWidgets('D-pad leaves profile name input and reaches actions', (tester) async {

test/screens/profile/profile_detail_screen_test.dart

@@ -30,10 +30,13 @@ void main() {
 
   tearDown(() {
     TvDetectionService.debugSetAppleTVOverride(null);
+    PlatformDetector.debugSetIsDesktopOSOverride(null);
   });
 
   testWidgets('remote back pops the manage profile page', (tester) async {
     TvDetectionService.debugSetAppleTVOverride(true);
+    // Simulated TV device, not desktop force-TV: keep locked keyboard mode.
+    PlatformDetector.debugSetIsDesktopOSOverride(false);
     final db = AppDatabase.forTesting(NativeDatabase.memory());
     final profile = Profile.local(id: 'local-owner', displayName: 'Owner', createdAt: DateTime(2026, 1, 1));
     final profiles = _FakeProfileRegistry(db, [profile]);

test/screens/settings/add_jellyfin_screen_test.dart

@@ -85,6 +85,7 @@ void main() {
   tearDown(() {
     TvDetectionService.debugSetAppleTVOverride(null);
     TvDetectionService.setForceTVSync(false);
+    PlatformDetector.debugSetIsDesktopOSOverride(null);
   });
 
   testWidgets('autofocuses the server URL field', (tester) async {
@@ -269,6 +270,8 @@ void main() {
     TvDetectionService.debugSetAppleTVOverride(null);
     await TvDetectionService.getInstance(forceTv: true);
     TvDetectionService.setForceTVSync(true);
+    // Simulated TV device, not desktop force-TV: keep locked keyboard mode.
+    PlatformDetector.debugSetIsDesktopOSOverride(false);
 
     await tester.pumpWidget(
       InputModeTracker(