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/handler/auth_handler_otp_test.go

@@ -23,10 +23,10 @@ func TestHandleKratosCourierRelay_Email(t *testing.T) {
 	app.Post("/api/v1/auth/kratos/courier", h.HandleKratosCourierRelay)
 
 	// Simulate Kratos Courier Request for Email
-	reqBody := map[string]interface{}{
+	reqBody := map[string]any{
 		"recipient":     "user@example.com",
 		"template_type": "verification_code",
-		"template_data": map[string]interface{}{
+		"template_data": map[string]any{
 			"verification_code": "123456",
 		},
 		"subject": "Verify your email",
@@ -50,7 +50,7 @@ func TestVerifySignupCode_Success(t *testing.T) {
 
 	// Mock stored code in redis
 	// signup:email:user@test.com -> {"code":"654321", "verified":false, "expires_at":...}
-	state := map[string]interface{}{
+	state := map[string]any{
 		"code":       "654321",
 		"verified":   false,
 		"expires_at": 9999999999, // far future
@@ -71,13 +71,13 @@ func TestVerifySignupCode_Success(t *testing.T) {
 	resp, _ := app.Test(req, -1)
 	assert.Equal(t, http.StatusOK, resp.StatusCode)
 
-	var res map[string]interface{}
+	var res map[string]any
 	json.NewDecoder(resp.Body).Decode(&res)
 	assert.True(t, res["success"].(bool))
 
 	// Check redis state updated to verified
 	val, _ := redis.Get("signup:email:user@test.com")
-	var updatedState map[string]interface{}
+	var updatedState map[string]any
 	json.Unmarshal([]byte(val), &updatedState)
 	assert.True(t, updatedState["verified"].(bool))
 }
@@ -90,7 +90,7 @@ func TestVerifySignupCode_Invalid(t *testing.T) {
 	app := fiber.New()
 	app.Post("/api/v1/auth/signup/verify", h.VerifySignupCode)
 
-	stateJSON, _ := json.Marshal(map[string]interface{}{
+	stateJSON, _ := json.Marshal(map[string]any{
 		"code":       "111111",
 		"expires_at": 9999999999,
 	})