fix(account): close create modal on success and make cookies optional

- AccountList.createAccount 成功后关闭创建弹窗（此前只提示不关闭）
- Cookies 前端改为可选：留空代表扫码登录场景，提交时不携带该字段
- 后端 validAccount 允许空凭据（此前 http.ParseCookie("") 直接拒绝）
- CreateAccount 空凭据时跳过 keyring 写入，不产生空值记录；回滚补偿仅在实际写入过凭据时执行

验证：go test ./... / go vet ./... / 双端构建通过；web vitest 66 用例通过（新增无 cookies 创建+弹窗关闭用例）；npm run build 通过

internal/phasea/store.go

@@ -273,15 +273,20 @@ func (s *Store) CreateAccount(ctx context.Context, account Account, credentials
 	if !validAccount(account) || credentials == nil {
 		return ErrInvalid
 	}
-	if err := credentials.Store(ctx, account.CredentialReference, account.CredentialKey, account.Cookies); err != nil {
-		storeErr := errors.New("store account credential")
-		if cleanupErr := credentials.Delete(context.WithoutCancel(ctx), account.CredentialReference, account.CredentialKey); cleanupErr != nil {
-			storeErr = errors.Join(storeErr, errors.New("delete incomplete account credential"))
+	// 空凭据（扫码登录场景）不写 keyring：凭据留待后续登录/同步链路补齐
+	stored := false
+	if account.Cookies != "" {
+		if err := credentials.Store(ctx, account.CredentialReference, account.CredentialKey, account.Cookies); err != nil {
+			storeErr := errors.New("store account credential")
+			if cleanupErr := credentials.Delete(context.WithoutCancel(ctx), account.CredentialReference, account.CredentialKey); cleanupErr != nil {
+				storeErr = errors.Join(storeErr, errors.New("delete incomplete account credential"))
+			}
+			return storeErr
 		}
-		return storeErr
+		stored = true
 	}
 	defer func() {
-		if err != nil && !errors.Is(err, ErrAccountCreationUnknown) {
+		if stored && err != nil && !errors.Is(err, ErrAccountCreationUnknown) {
 			if cleanupErr := credentials.Delete(context.WithoutCancel(ctx), account.CredentialReference, account.CredentialKey); cleanupErr != nil {
 				err = errors.Join(err, errors.New("delete orphaned account credential"))
 			}
@@ -393,8 +398,13 @@ func validAccount(account Account) bool {
 			return false
 		}
 	}
-	_, err := http.ParseCookie(account.Cookies)
-	return err == nil
+	// 空凭据合法（扫码登录场景）；非空时才校验 Cookie Header 格式
+	if account.Cookies != "" {
+		if _, err := http.ParseCookie(account.Cookies); err != nil {
+			return false
+		}
+	}
+	return true
 }
 
 func (s *Store) CreateDraft(ctx context.Context, draft Draft) error {

internal/phasea/store_test.go

@@ -79,6 +79,11 @@ func TestValidationRejectsInvalidInputsBeforePersistence(t *testing.T) {
 			t.Fatalf("supported platform rejected: %s", platform)
 		}
 	}
+	empty := valid
+	empty.Cookies = ""
+	if !validAccount(empty) {
+		t.Fatal("empty cookies must stay valid (scan-to-login account)")
+	}
 	for name, mutate := range map[string]func(*Account){
 		"id":                   func(account *Account) { account.ID = "INVALID" },
 		"name":                 func(account *Account) { account.Name = " " },
@@ -725,6 +730,38 @@ func TestPhaseAOfflineWorkflow(t *testing.T) {
 	}
 }
 
+func TestCreateAccountWithoutCookiesSkipsCredentialStore(t *testing.T) {
+	databaseURL := os.Getenv("CREATORHUB_POSTGRES_TEST_URL")
+	if databaseURL == "" {
+		t.Skip("set CREATORHUB_POSTGRES_TEST_URL to run PostgreSQL integration coverage")
+	}
+	ctx := context.Background()
+	store, err := Open(ctx, databaseURL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = store.Close() })
+	applyHubMigrationsForPhaseATest(t, store)
+	if _, err := store.db.ExecContext(ctx, `
+		TRUNCATE audit_event, execution_attempt, operation_task, confirmation, content_draft,
+			runtime_instance, environment_binding, network_exit, social_account, credential_reference,
+			browser_env, browser_image, gateway RESTART IDENTITY CASCADE`); err != nil {
+		t.Fatal(err)
+	}
+	credentials := &testCredentialBridge{values: map[string]string{}}
+	account := Account{ID: "account-no-cookies", Name: "扫码账号", Platform: "douyin", PlatformAccountKey: "qr-login",
+		Tags: []string{}, Cookies: "",
+		CredentialReference: CredentialReference{ID: "account-no-cookies-cookies", Provider: "os_keyring"}, CredentialKey: "creatorhub/account-no-cookies/cookies"}
+	if err := store.CreateAccount(ctx, account, credentials); err != nil {
+		t.Fatalf("creating an account without cookies failed: %v", err)
+	}
+	if _, stored := credentials.values[account.CredentialKey]; stored {
+		t.Fatal("empty cookies must not be written to the credential provider")
+	}
+	assertCount(t, store, `SELECT count(*) FROM social_account WHERE id = $1`, 1, account.ID)
+	assertCount(t, store, `SELECT count(*) FROM credential_reference WHERE id = $1`, 1, account.CredentialReference.ID)
+}
+
 func TestAccountCredentialCommitResult(t *testing.T) {
 	databaseURL := os.Getenv("CREATORHUB_POSTGRES_TEST_URL")
 	if databaseURL == "" {