feat: 新增退款管理模块 — 完整的退款审批流程、佣金回扣和资产重置

新增退款申请全生命周期管理：创建/列表/详情/审批通过/拒绝/退回/重新提交
审批通过后异步执行佣金全额回扣（扣减各代理佣金钱包）和资产重置（套餐失效+停机+世代重置）
新增 tb_refund_request 表（迁移 000093）、RefundRequest Model、8 个 DTO
新增 Store/Service/Handler/路由注册，仅平台用户可访问

internal/store/postgres/refund_store.go

@@ -0,0 +1,119 @@
+package postgres
+
+import (
+	"context"
+
+	"github.com/break/junhong_cmp_fiber/internal/model"
+	"github.com/break/junhong_cmp_fiber/internal/store"
+	"github.com/break/junhong_cmp_fiber/pkg/constants"
+	"github.com/break/junhong_cmp_fiber/pkg/middleware"
+	"gorm.io/gorm"
+)
+
+// RefundListFilters 退款列表筛选条件
+type RefundListFilters struct {
+	Status  *int  `json:"status"`
+	OrderID *uint `json:"order_id"`
+	ShopID  *uint `json:"shop_id"`
+}
+
+// RefundStore 退款申请数据访问层
+type RefundStore struct {
+	db *gorm.DB
+}
+
+// NewRefundStore 创建退款申请 Store 实例
+func NewRefundStore(db *gorm.DB) *RefundStore {
+	return &RefundStore{db: db}
+}
+
+// Create 创建退款申请记录
+func (s *RefundStore) Create(ctx context.Context, req *model.RefundRequest) error {
+	return s.db.WithContext(ctx).Create(req).Error
+}
+
+// GetByID 根据 ID 查询退款申请（含数据权限过滤）
+func (s *RefundStore) GetByID(ctx context.Context, id uint) (*model.RefundRequest, error) {
+	var req model.RefundRequest
+	query := s.db.WithContext(ctx).Where("id = ?", id)
+	query = middleware.ApplyShopFilter(ctx, query)
+	if err := query.First(&req).Error; err != nil {
+		return nil, err
+	}
+	return &req, nil
+}
+
+// Update 更新退款申请记录（全字段保存）
+func (s *RefundStore) Update(ctx context.Context, req *model.RefundRequest) error {
+	return s.db.WithContext(ctx).Save(req).Error
+}
+
+// UpdateFields 按字段更新退款申请（用于条件更新场景）
+func (s *RefundStore) UpdateFields(ctx context.Context, id uint, updates map[string]any) error {
+	return s.db.WithContext(ctx).
+		Model(&model.RefundRequest{}).
+		Where("id = ?", id).
+		Updates(updates).Error
+}
+
+// List 分页查询退款申请列表（含数据权限过滤和筛选条件）
+func (s *RefundStore) List(ctx context.Context, opts *store.QueryOptions, filters *RefundListFilters) ([]*model.RefundRequest, int64, error) {
+	var requests []*model.RefundRequest
+	var total int64
+
+	query := s.db.WithContext(ctx).Model(&model.RefundRequest{})
+	query = middleware.ApplyShopFilter(ctx, query)
+
+	if filters != nil {
+		if filters.Status != nil {
+			query = query.Where("status = ?", *filters.Status)
+		}
+		if filters.OrderID != nil {
+			query = query.Where("order_id = ?", *filters.OrderID)
+		}
+		if filters.ShopID != nil {
+			query = query.Where("shop_id = ?", *filters.ShopID)
+		}
+	}
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	if opts == nil {
+		opts = &store.QueryOptions{
+			Page:     1,
+			PageSize: constants.DefaultPageSize,
+		}
+	}
+	offset := (opts.Page - 1) * opts.PageSize
+	query = query.Offset(offset).Limit(opts.PageSize)
+
+	if opts.OrderBy != "" {
+		query = query.Order(opts.OrderBy)
+	} else {
+		query = query.Order("created_at DESC")
+	}
+
+	if err := query.Find(&requests).Error; err != nil {
+		return nil, 0, err
+	}
+
+	return requests, total, nil
+}
+
+// FindActiveByOrderID 查找订单关联的活跃退款申请（状态为待审批、已通过、已退回）
+func (s *RefundStore) FindActiveByOrderID(ctx context.Context, orderID uint) (*model.RefundRequest, error) {
+	var req model.RefundRequest
+	err := s.db.WithContext(ctx).
+		Where("order_id = ? AND status IN ?", orderID, []int{
+			model.RefundStatusPending,
+			model.RefundStatusApproved,
+			model.RefundStatusReturned,
+		}).
+		First(&req).Error
+	if err != nil {
+		return nil, err
+	}
+	return &req, nil
+}