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/shared/config/config_test.go

@@ -89,6 +89,30 @@ retrieval:
 	}
 }
 
+func TestLoadAppliesBrandLibraryDefaults(t *testing.T) {
+	configPath := writeTestConfig(t, `
+brand_library: {}
+`)
+
+	cfg, err := Load(configPath)
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+
+	if cfg.BrandLibrary.FreeBrandLimit != 1 {
+		t.Fatalf("expected default free brand limit 1, got %d", cfg.BrandLibrary.FreeBrandLimit)
+	}
+	if cfg.BrandLibrary.PaidBrandLimit != 2 {
+		t.Fatalf("expected default paid brand limit 2, got %d", cfg.BrandLibrary.PaidBrandLimit)
+	}
+	if cfg.BrandLibrary.MaxKeywords != 5 {
+		t.Fatalf("expected default max keywords 5, got %d", cfg.BrandLibrary.MaxKeywords)
+	}
+	if cfg.BrandLibrary.MaxQuestionsPerKeyword != 5 {
+		t.Fatalf("expected default max questions per keyword 5, got %d", cfg.BrandLibrary.MaxQuestionsPerKeyword)
+	}
+}
+
 func writeTestConfig(t *testing.T, body string) string {
 	t.Helper()