feat(user): support fixed UUID registration and enhance bulk import results

- Added support for fixed UUIDs during bulk registration (Search-first + ExternalID mapping)
- Implemented idempotency and visibility restoration for soft-deleted users
- Enhanced bulk upload UI to show 'New/Updated/Unchanged' status and modified fields
- Added logic to reclaim identifiers (login_id) from colliding records
- Added frontend E2E and backend unit tests for UUID integrity and conflict handling
- Fixed i18n, formatting, and mock tests to satisfy code-check
- Applied 'go fix' for 'omitzero' tags and general Go standards

backend/internal/bootstrap/admin_account.go

@@ -136,7 +136,7 @@ func buildSuperAdminBrokerUser(email, name string) *domain.BrokerUser {
 		Email:       email,
 		Name:        name,
 		PhoneNumber: "",
-		Attributes: map[string]interface{}{
+		Attributes: map[string]any{
 			"department":      "Admin",
 			"affiliationType": "internal",
 			"grade":           "",
@@ -170,7 +170,7 @@ func (s *gormSuperAdminStore) CreateUser(ctx context.Context, user *domain.User)
 }
 
 func (s *gormSuperAdminStore) UpdateUserSuperAdmin(ctx context.Context, userID string, name string) (*domain.User, error) {
-	updates := map[string]interface{}{
+	updates := map[string]any{
 		"role":       domain.RoleSuperAdmin,
 		"status":     domain.UserStatusActive,
 		"updated_at": time.Now(),