fix: templateService return format and Templates page array handling

- Updated templateService to return response.data like other services
- Added fallback to empty array in Templates.jsx to prevent map errors
- Ensures consistency across all service modules

frontend/src/pages/Templates.jsx

@@ -63,10 +63,11 @@ function Templates() {
     try {
       setLoading(true);
       const response = await templateService.getAll();
-      setTemplates(response.data);
+      setTemplates(response.data || []);
     } catch (error) {
       console.error('Failed to load templates:', error);
       alert('Şablonlar yüklenemedi');
+      setTemplates([]);
     } finally {
       setLoading(false);
     }