feat: optimize tenant admin view and enhance user list with dynamic columns and metadata search

backend/internal/repository/user_repository.go

@@ -176,7 +176,9 @@ func (r *userRepository) List(ctx context.Context, offset, limit int, search str
 
 	if search != "" {
 		searchTerm := "%" + search + "%"
-		db = db.Where("(email LIKE ? OR name LIKE ? OR company_code LIKE ?)", searchTerm, searchTerm, searchTerm)
+		// Search in basic fields and metadata (PostgreSQL JSONB)
+		db = db.Where("(email LIKE ? OR name LIKE ? OR company_code LIKE ? OR metadata::text LIKE ?)", 
+			searchTerm, searchTerm, searchTerm, searchTerm)
 	}
 
 	if err := db.Count(&total).Error; err != nil {