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

locales/ko.toml

@@ -2203,6 +2203,17 @@ additional = "추가 소속/관리 테넌트"
 primary = "대표 소속 테넌트"
 title = "소속 및 조직 정보"
 
+[ui.admin.users.field]
+department = "부서"
+grade = "직급"
+jobtitle = "직무"
+name = "이름"
+phone = "전화번호"
+position = "직책"
+role = "역할"
+status = "상태"
+tenant = "테넌트"
+
 [ui.admin.users.list]
 add = "사용자 추가"
 bulk_import = "일괄 임포트"
@@ -3300,6 +3311,8 @@ title = "회사별 앱별 로그인 요청 현황"
 export = "내보내기"
 
 [ui.admin.users.bulk]
+modified_fields = "수정 항목:"
+no_changes = "변경 사항 없음"
 permission_placeholder = "권한 선택"
 status_placeholder = "상태 선택"