feat(marketing): add user logo management module

Users can now save uploaded logos to the backend (marketing_user_logos table),
avoiding repeated uploads. Includes CRUD endpoints: list, save, delete with
a per-user limit of 10 logos.

Made-with: Cursor

internal/marketing/service/user_logo_service.go

@@ -0,0 +1,55 @@
+package service
+
+import (
+	"errors"
+
+	"wx_service/internal/marketing/model"
+	"wx_service/internal/marketing/repository"
+)
+
+const MaxLogosPerUser = 10
+
+var ErrLogoLimitReached = errors.New("Logo 数量已达上限")
+
+type UserLogoService struct {
+	repo *repository.UserLogoRepository
+}
+
+func NewUserLogoService(repo *repository.UserLogoRepository) *UserLogoService {
+	return &UserLogoService{repo: repo}
+}
+
+type SaveLogoRequest struct {
+	URL      string `json:"url" binding:"required"`
+	Filename string `json:"filename"`
+	FileSize int64  `json:"file_size"`
+}
+
+func (s *UserLogoService) Save(userID uint, req SaveLogoRequest) (*model.UserLogo, error) {
+	count, err := s.repo.CountByUser(userID)
+	if err != nil {
+		return nil, err
+	}
+	if count >= MaxLogosPerUser {
+		return nil, ErrLogoLimitReached
+	}
+
+	logo := &model.UserLogo{
+		UserID:   userID,
+		URL:      req.URL,
+		Filename: req.Filename,
+		FileSize: req.FileSize,
+	}
+	if err := s.repo.Create(logo); err != nil {
+		return nil, err
+	}
+	return logo, nil
+}
+
+func (s *UserLogoService) List(userID uint) ([]model.UserLogo, error) {
+	return s.repo.FindByUser(userID)
+}
+
+func (s *UserLogoService) Delete(id, userID uint) error {
+	return s.repo.Delete(id, userID)
+}