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/routes/admin.go

@@ -122,4 +122,7 @@ func RegisterAdminRoutes(router fiber.Router, handlers *bootstrap.Handlers, midd
 	if handlers.AgentRecharge != nil {
 		registerAgentRechargeRoutes(authGroup, handlers.AgentRecharge, doc, basePath)
 	}
+	if handlers.Refund != nil {
+		registerRefundRoutes(authGroup, handlers.Refund, doc, basePath)
+	}
 }

internal/routes/refund.go

@@ -0,0 +1,81 @@
+package routes
+
+import (
+	"github.com/gofiber/fiber/v2"
+
+	"github.com/break/junhong_cmp_fiber/internal/handler/admin"
+	"github.com/break/junhong_cmp_fiber/internal/model/dto"
+	"github.com/break/junhong_cmp_fiber/pkg/constants"
+	"github.com/break/junhong_cmp_fiber/pkg/errors"
+	"github.com/break/junhong_cmp_fiber/pkg/middleware"
+	"github.com/break/junhong_cmp_fiber/pkg/openapi"
+)
+
+// registerRefundRoutes 注册退款管理路由
+// 仅平台用户（超级管理员和平台用户）可访问
+func registerRefundRoutes(router fiber.Router, handler *admin.RefundHandler, doc *openapi.Generator, basePath string) {
+	refund := router.Group("/refunds", func(c *fiber.Ctx) error {
+		userType := middleware.GetUserTypeFromContext(c.UserContext())
+		if userType != constants.UserTypeSuperAdmin && userType != constants.UserTypePlatform {
+			return errors.New(errors.CodeForbidden, "无权限访问退款管理功能")
+		}
+		return c.Next()
+	})
+	groupPath := basePath + "/refunds"
+
+	Register(refund, doc, groupPath, "POST", "/", handler.Create, RouteSpec{
+		Summary: "创建退款申请",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.CreateRefundRequest),
+		Output:  new(dto.RefundResponse),
+		Auth:    true,
+	})
+
+	Register(refund, doc, groupPath, "GET", "/", handler.List, RouteSpec{
+		Summary: "退款申请列表",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.RefundListRequest),
+		Output:  new(dto.RefundListResponse),
+		Auth:    true,
+	})
+
+	Register(refund, doc, groupPath, "GET", "/:id", handler.GetByID, RouteSpec{
+		Summary: "退款申请详情",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.RefundIDRequest),
+		Output:  new(dto.RefundResponse),
+		Auth:    true,
+	})
+
+	Register(refund, doc, groupPath, "POST", "/:id/approve", handler.Approve, RouteSpec{
+		Summary: "审批通过退款申请",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.ApproveRefundRequest),
+		Output:  nil,
+		Auth:    true,
+	})
+
+	Register(refund, doc, groupPath, "POST", "/:id/reject", handler.Reject, RouteSpec{
+		Summary: "审批拒绝退款申请",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.RejectRefundRequest),
+		Output:  nil,
+		Auth:    true,
+	})
+
+	Register(refund, doc, groupPath, "POST", "/:id/return", handler.Return, RouteSpec{
+		Summary: "退回退款申请",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.ReturnRefundRequest),
+		Output:  nil,
+		Auth:    true,
+	})
+
+	Register(refund, doc, groupPath, "POST", "/:id/resubmit", handler.Resubmit, RouteSpec{
+		Summary: "重新提交退款申请",
+		Tags:    []string{"退款管理"},
+		Input:   new(dto.ResubmitRefundRequest),
+		Output:  nil,
+		Auth:    true,
+	})
+}