拆分 service 与前端大文件,修复 CORS 配置与格式问题

- 后端 internal/service 按职责拆分:
  fulfillment.go(1397→527)拆出 wallet/timeout/data/order/query/dashboard/shipnotify
  delivery.go(1124→801)拆出 upstream/link/state/helpers
  merchant.go(855→251)拆出 member/product/api_client/catalog/helpers
- 前端 MerchantCenter.tsx(1327→606)拆出 merchantCenterTabs/merchantCenterUtils
- docker-compose backend 透传 CORS_ALLOWED_ORIGINS
- CORS 白名单实现(config/router/README/.env.example 配套)
- 修复 gofmt 与文件尾部多余空行

backend/internal/service/merchant_member.go

@@ -0,0 +1,64 @@
+package service
+
+import (
+	"errors"
+	"fmt"
+
+	"affiliate_dash/internal/model"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+)
+
+type AddMemberInput struct {
+	UserID    uint
+	Role      string
+	IsDefault bool
+}
+
+func (s *MerchantService) AddMember(merchantID uint, in AddMemberInput, actorUserID uint) (*model.MerchantMember, error) {
+	if !isValidMemberRole(in.Role) {
+		return nil, errors.New("无效的商户成员角色")
+	}
+	member := &model.MerchantMember{
+		MerchantID: merchantID,
+		UserID:     in.UserID,
+		Role:       in.Role,
+		Status:     1,
+		IsDefault:  in.IsDefault,
+	}
+	err := s.db.Transaction(func(tx *gorm.DB) error {
+		var merchant model.Merchant
+		if err := tx.Where("id = ? AND status = ?", merchantID, model.MerchantStatusActive).First(&merchant).Error; err != nil {
+			return errors.New("商户不存在或已禁用")
+		}
+		var user model.User
+		if err := tx.Where("id = ? AND status = ?", in.UserID, 1).First(&user).Error; err != nil {
+			return errors.New("用户不存在或已禁用")
+		}
+		if err := tx.Clauses(clause.OnConflict{
+			Columns: []clause.Column{{Name: "merchant_id"}, {Name: "user_id"}},
+			DoUpdates: clause.Assignments(map[string]interface{}{
+				"role":       in.Role,
+				"status":     1,
+				"is_default": in.IsDefault,
+			}),
+		}).Create(member).Error; err != nil {
+			return err
+		}
+		return writeAudit(tx, &merchantID, &actorUserID, nil, "merchant.member.upsert", "merchant_member", fmt.Sprintf("%d:%d", merchantID, in.UserID), map[string]string{"role": in.Role})
+	})
+	if err != nil {
+		return nil, err
+	}
+	if err := s.db.Where("merchant_id = ? AND user_id = ?", merchantID, in.UserID).First(member).Error; err != nil {
+		return nil, err
+	}
+	return member, nil
+}
+
+func (s *MerchantService) ListMembers(merchantID uint) ([]model.MerchantMember, error) {
+	var members []model.MerchantMember
+	err := s.db.Preload("User").Where("merchant_id = ?", merchantID).Order("id ASC").Find(&members).Error
+	return members, err
+}