feat(limitation): add saved filter limit check to ContentLimitationService

Extends the `ContentLimitationService` to enforce limits on saving new filters.

This change adds a `saveFilter` case to the `ContentAction` enum and implements the corresponding logic within the `checkAction` method. It reads the user's role and the number of currently saved filters, comparing it against the role-specific limit defined in the remote configuration (`guestSavedFiltersLimit`, `authenticatedSavedFiltersLimit`, `premiumSavedFiltersLimit`).

This centralizes the business rule for filter limits, ensuring it can be applied consistently across the app.

Author: fulleni

lib/shared/services/content_limitation_service.dart

@@ -15,6 +15,9 @@ enum ContentAction {
 
   /// The action of following a country.
   followCountry,
+
+  /// The action of saving a filter.
+  saveFilter,
 }
 
 /// Defines the outcome of a content limitation check.
@@ -82,6 +85,21 @@ class ContentLimitationService {
           return _getLimitationStatusForRole(role);
         }
 
+      // Check if the user has reached the limit for saving filters.
+      case ContentAction.saveFilter:
+        final count = preferences.savedFilters.length;
+        final int limit;
+        switch (role) {
+          case AppUserRole.guestUser:
+            limit = limits.guestSavedFiltersLimit;
+          case AppUserRole.standardUser:
+            limit = limits.authenticatedSavedFiltersLimit;
+          case AppUserRole.premiumUser:
+            limit = limits.premiumSavedFiltersLimit;
+        }
+        if (count >= limit) {
+          return _getLimitationStatusForRole(role);
+        }
       case ContentAction.followTopic:
       case ContentAction.followSource:
       case ContentAction.followCountry:
@@ -107,6 +125,9 @@ class ContentLimitationService {
           case ContentAction.bookmarkHeadline:
             // This case is handled above and will not be reached here.
             count = 0;
+          case ContentAction.saveFilter:
+            // This case is handled above and will not be reached here.
+            count = 0;
         }
 
         if (count >= limit) {