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/utils/password_policy.go

@@ -4,6 +4,8 @@ import (
 	"baron-sso-backend/internal/domain"
 	"crypto/rand"
 	"fmt"
+	"slices"
+	"strings"
 )
 
 const (
@@ -111,13 +113,7 @@ func GeneratePasswordWithPolicy(policy *domain.PasswordPolicy) (string, error) {
 	if additionalTypes > 0 {
 		pool := make([]string, 0, len(selected))
 		for _, cat := range selected {
-			isRequired := false
-			for _, req := range required {
-				if req == cat {
-					isRequired = true
-					break
-				}
-			}
+			isRequired := slices.Contains(required, cat)
 			if !isRequired {
 				pool = append(pool, cat)
 			}
@@ -150,12 +146,12 @@ func GeneratePasswordWithPolicy(policy *domain.PasswordPolicy) (string, error) {
 		passwordRunes = append(passwordRunes, ch)
 	}
 
-	combined := ""
+	var combined strings.Builder
 	for _, charset := range selected {
-		combined += charset
+		combined.WriteString(charset)
 	}
 	for len(passwordRunes) < minLength {
-		ch, err := randomChar(combined)
+		ch, err := randomChar(combined.String())
 		if err != nil {
 			return "", err
 		}