feat: add brand library management features

- Introduced BrandLibrarySummary type to encapsulate brand library limits and usage.
- Updated Brand interface to include keyword_count and question_count fields.
- Implemented brand library limits in the backend, including max brands, keywords, and questions per keyword.
- Added API endpoint to retrieve brand library summary.
- Enhanced BrandsView.vue to display brand library usage and limits.
- Implemented computed properties to manage brand, keyword, and question limits in the UI.
- Updated mutation handlers to invalidate relevant queries upon creating/updating brands, keywords, and questions.
- Added visual indicators for brand, keyword, and question limits in the UI.
- Enhanced error handling for exceeding brand and keyword limits during creation.

server/internal/tenant/transport/router_test.go

@@ -29,6 +29,7 @@ func TestProtectedRoutes_RequireAuth(t *testing.T) {
 		{http.MethodGet, "/api/tenant/templates"},
 		{http.MethodGet, "/api/tenant/articles"},
 		{http.MethodGet, "/api/tenant/brands"},
+		{http.MethodGet, "/api/tenant/brands/library-summary"},
 		{http.MethodGet, "/api/tenant/monitoring/brands/:brand_id/questions/:question_id/detail"},
 		{http.MethodPost, "/api/tenant/brands"},
 	}