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/logger/client_log_policy_test.go

@@ -57,15 +57,15 @@ func TestShouldFilterNoisyClientInfo(t *testing.T) {
 }
 
 func TestSanitizeClientLogData(t *testing.T) {
-	input := map[string]interface{}{
+	input := map[string]any{
 		"token": "raw-token",
 		"safe":  "ok",
-		"nested": map[string]interface{}{
+		"nested": map[string]any{
 			"new_password": "secret-1",
 			"path":         "/ko/profile",
 		},
-		"arr": []interface{}{
-			map[string]interface{}{"authorization": "Bearer abc"},
+		"arr": []any{
+			map[string]any{"authorization": "Bearer abc"},
 			"token=abc123",
 		},
 	}
@@ -75,12 +75,12 @@ func TestSanitizeClientLogData(t *testing.T) {
 	assert.Equal(t, "*****", result["token"])
 	assert.Equal(t, "ok", result["safe"])
 
-	nested := result["nested"].(map[string]interface{})
+	nested := result["nested"].(map[string]any)
 	assert.Equal(t, "*****", nested["new_password"])
 	assert.Equal(t, "/ko/profile", nested["path"])
 
-	arr := result["arr"].([]interface{})
-	first := arr[0].(map[string]interface{})
+	arr := result["arr"].([]any)
+	first := arr[0].(map[string]any)
 	assert.Equal(t, "*****", first["authorization"])
 	assert.Equal(t, "token=*****", arr[1])
 }