refactor(dependencies): simplify JSON deserialization functions

- Replace lambda functions with direct method references for improved readability
- Update userAppSettingsRepository and userContentPreferencesRepository initializers

Author: fulleni

lib/src/config/app_dependencies.dart

@@ -165,7 +165,7 @@ class AppDependencies {
     userAppSettingsRepository = _createRepository(
       connection,
       'user_app_settings',
-      (json) => UserAppSettings.fromJson(json),
+      UserAppSettings.fromJson,
       (settings) {
         final json = settings.toJson();
         // These fields are complex objects and must be JSON encoded for the DB.
@@ -177,7 +177,7 @@ class AppDependencies {
     userContentPreferencesRepository = _createRepository(
       connection,
       'user_content_preferences',
-      (json) => UserContentPreferences.fromJson(json),
+      UserContentPreferences.fromJson,
       (preferences) {
         final json = preferences.toJson();
         // These fields are lists of complex objects and must be JSON encoded.