优化商户管理, 增加商户名重置密码等等

backend/internal/handler/merchant.go

@@ -741,6 +741,56 @@ func (h *MerchantHandler) AddPlatformMerchantMember(c *gin.Context) {
 	response.OK(c, member)
 }
 
+// AdminGetMerchantAccount 平台管理员查看指定商户的负责人登录账号。
+func (h *MerchantHandler) AdminGetMerchantAccount(c *gin.Context) {
+	id, _ := strconv.ParseUint(c.Param("id"), 10, 64)
+	if id == 0 {
+		response.BadRequest(c, "商户 ID 无效")
+		return
+	}
+	accounts, err := h.merchantSvc.ListOwnerAccounts(uint(id))
+	if err != nil {
+		response.ServerError(c, err.Error())
+		return
+	}
+	response.OK(c, accounts)
+}
+
+type adminUpdateMerchantAccountReq struct {
+	UserID   uint   `json:"user_id" binding:"required"`
+	Username string `json:"username" binding:"required,min=3,max=64"`
+	Nickname string `json:"nickname" binding:"max=64"`
+	Password string `json:"password" binding:"omitempty,min=6,max=128"`
+	Status   *int   `json:"status"`
+}
+
+// AdminUpdateMerchantAccount 平台管理员维护指定商户的负责人登录账号：
+// 修改用户名/昵称、重置密码、启用停用；密码留空表示不重置。
+func (h *MerchantHandler) AdminUpdateMerchantAccount(c *gin.Context) {
+	id, _ := strconv.ParseUint(c.Param("id"), 10, 64)
+	var req adminUpdateMerchantAccountReq
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "参数错误：用户名必填（3-64 位），密码至少 6 位")
+		return
+	}
+	if id == 0 {
+		response.BadRequest(c, "商户 ID 无效")
+		return
+	}
+	account, err := h.merchantSvc.UpdateMerchantOwnerAccount(uint(id), service.UpdateMerchantOwnerAccountInput{
+		UserID:   req.UserID,
+		Username: req.Username,
+		Nickname: req.Nickname,
+		Password: req.Password,
+		Status:   req.Status,
+	}, middleware.GetUserID(c))
+	if err != nil {
+		response.BadRequest(c, err.Error())
+		return
+	}
+	response.OK(c, account)
+}
+
 func pageParams(c *gin.Context) (int, int) {
 	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
 	size, _ := strconv.Atoi(c.DefaultQuery("size", "20"))