feat: implement multi-identifier architecture (Issue #496)

- Database: Add user_login_ids table for 1:N identifier mapping and remove legacy login_id column
- Kratos: Update identity schema to use custom_login_ids array instead of a single id trait
- Backend: Implement syncCustomLoginIDs to collect isLoginId fields across tenant schemas
- Backend: Add backtracking logic to auto-assign session tenant based on used login identifier
- Backend: Add 409 Conflict exception handling for Create/Update operations
- AdminFront: Refactor UserDetailPage to a tabbed grid layout (Info, Tenants, Security)
- AdminFront: Show '로그인 ID' badge on tenant schema fields used for authentication
- UserFront: Remove legacy optional 'Login ID' input from signup flow
- Tests: Add multi-identifier repository tests and update handler tests

backend/internal/handler/dev_handler.go

@@ -4,6 +4,7 @@ import (
 	"baron-sso-backend/internal/domain"
 	"baron-sso-backend/internal/repository"
 	"baron-sso-backend/internal/service"
+	"baron-sso-backend/internal/utils"
 	"context"
 	"crypto/rand"
 	"encoding/base64"
@@ -2106,7 +2107,7 @@ func (h *DevHandler) matchesDevAuditFilter(
 	if !strings.Contains(logItem.EventType, "/api/v1/dev/") {
 		return false
 	}
-	details, _ := parseAuditDetails(logItem.Details)
+	details, _ := utils.ParseAuditDetails(logItem.Details)
 	if statusFilter != "" && statusFilter != "all" && strings.ToLower(logItem.Status) != statusFilter {
 		return false
 	}