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/validator/schema_validator.go

@@ -8,7 +8,7 @@ import (
 )
 
 // ValidateIDPCompatibility checks if the provided IDP supports all required fields defined in the BrokerUser model.
-func ValidateIDPCompatibility(brokerModel interface{}, idp domain.IdentityProvider) error {
+func ValidateIDPCompatibility(brokerModel any, idp domain.IdentityProvider) error {
 	metadata, err := idp.GetMetadata()
 	if err != nil {
 		return fmt.Errorf("failed to fetch metadata from IDP %s: %w", idp.Name(), err)
@@ -20,12 +20,12 @@ func ValidateIDPCompatibility(brokerModel interface{}, idp domain.IdentityProvid
 	}
 
 	t := reflect.TypeOf(brokerModel)
-	if t.Kind() == reflect.Ptr {
+	if t.Kind() == reflect.Pointer {
 		t = t.Elem()
 	}
 
-	for i := 0; i < t.NumField(); i++ {
-		field := t.Field(i)
+	for field := range t.Fields() {
+		field := field
 
 		// Check "required" tag
 		isRequired := field.Tag.Get("required") == "true"
@@ -47,8 +47,8 @@ func ValidateIDPCompatibility(brokerModel interface{}, idp domain.IdentityProvid
 		if fieldName == "attributes" {
 			reqKeys := field.Tag.Get("required_keys")
 			if reqKeys != "" {
-				keys := strings.Split(reqKeys, ",")
-				for _, key := range keys {
+				keys := strings.SplitSeq(reqKeys, ",")
+				for key := range keys {
 					key = strings.TrimSpace(key)
 					if !supportedMap[key] {
 						return fmt.Errorf("IDP %s does not support required custom attribute: %s", idp.Name(), key)