修复外部邮箱更换回归用例的函数签名适配

为含可选分组写入保护参数的方法添加用例调用适配，不改变业务授权逻辑或中文提示。后端全量静态检查通过，未执行回归用例或实机验收。

backend/services/externalemail/repository_test.go

@@ -196,8 +196,12 @@ func TestRepositoryRebindsDisabledEmailWithFreshVerification(t *testing.T) {
 			bind := repo.Bind
 			verify := repo.Verify
 			if replacement {
-				bind = repo.BeginReplacement
-				verify = repo.VerifyReplacement
+				bind = func(request BindRequest) (*models.ExternalEmail, error) {
+					return repo.BeginReplacement(request)
+				}
+				verify = func(userID, id int) error {
+					return repo.VerifyReplacement(userID, id)
+				}
 			}
 			request := BindRequest{UserID: 1, Email: "OWNER@example.com", Type: models.ExternalEmailTypePrimary}
 			if _, err := bind(request); err != ErrBindingExists {