Add live room preview thumbnails

frontend/lib/providers/settings_provider.dart

@@ -12,10 +12,12 @@ class SettingsProvider with ChangeNotifier {
   String _baseUrl = _defaultUrl;
   Color _themeColor = Colors.blue;
   ThemeMode _themeMode = ThemeMode.system;
+  bool _livePreviewThumbnailsEnabled = false;
 
   String get baseUrl => _baseUrl;
   Color get themeColor => _themeColor;
   ThemeMode get themeMode => _themeMode;
+  bool get livePreviewThumbnailsEnabled => _livePreviewThumbnailsEnabled;
 
   SettingsProvider() {
     _loadSettings();
@@ -32,6 +34,8 @@ class SettingsProvider with ChangeNotifier {
     if (savedThemeMode != null) {
       _themeMode = _themeModeFromString(savedThemeMode);
     }
+    _livePreviewThumbnailsEnabled =
+        prefs.getBool('livePreviewThumbnailsEnabled') ?? false;
     notifyListeners();
   }
 
@@ -56,6 +60,13 @@ class SettingsProvider with ChangeNotifier {
     notifyListeners();
   }
 
+  void setLivePreviewThumbnailsEnabled(bool enabled) async {
+    _livePreviewThumbnailsEnabled = enabled;
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setBool('livePreviewThumbnailsEnabled', enabled);
+    notifyListeners();
+  }
+
   // Also provide the RTMP URL based on the same hostname
   String get rtmpUrl {
     final uri = Uri.parse(_baseUrl);
@@ -84,6 +95,16 @@ class SettingsProvider with ChangeNotifier {
     return "$rtmpUrl/$roomId/$normalizedQuality";
   }
 
+  String thumbnailUrl(String roomId, {String? cacheBuster}) {
+    final uri = Uri.parse(_baseUrl);
+    return uri
+        .replace(
+          path: '/api/rooms/$roomId/thumbnail',
+          queryParameters: cacheBuster == null ? null : {'t': cacheBuster},
+        )
+        .toString();
+  }
+
   ThemeMode _themeModeFromString(String value) {
     switch (value) {
       case 'light':