feat(auth): 接入 DCAuth v2 登录并完善成员管理

- 登录链路改为用户名 + 密码 + 短信验证码 + DCAuth v2 设备签名
- 迁移 014：新增 login_sms_codes / user_devices / device_challenges 与 users.phone
- 新增 /api/dcauth/authorize 与 challenge 状态轮询；旧密码登录仅放行未绑定手机号的账号
- 成员管理支持手机号绑定、设备重置、账号改名、昵称与重置密码
- 移除最后一个商户关系时软删除账号，释放用户名、手机号并撤销设备绑定

backend/internal/handler/merchant_member.go

@@ -50,9 +50,12 @@ func (h *MerchantHandler) AddCurrentMerchantMember(c *gin.Context) {
 }
 
 type updateMemberReq struct {
-	Role      string `json:"role" binding:"required"`
-	Status    int    `json:"status"`
-	IsDefault bool   `json:"is_default"`
+	Username  string  `json:"username"`
+	Password  string  `json:"password"`
+	Nickname  *string `json:"nickname"`
+	Role      string  `json:"role" binding:"required"`
+	Status    int     `json:"status"`
+	IsDefault bool    `json:"is_default"`
 }
 
 func (h *MerchantHandler) UpdateCurrentMerchantMember(c *gin.Context) {
@@ -63,6 +66,7 @@ func (h *MerchantHandler) UpdateCurrentMerchantMember(c *gin.Context) {
 		return
 	}
 	member, err := h.merchantSvc.UpdateMember(middleware.GetMerchantID(c), uint(memberID), service.UpdateMemberInput{
+		Username: req.Username, Password: req.Password, Nickname: req.Nickname,
 		Role: req.Role, Status: req.Status, IsDefault: req.IsDefault,
 	}, middleware.GetUserID(c))
 	if err != nil {
@@ -132,3 +136,42 @@ func (h *MerchantHandler) UpdateRole(c *gin.Context) {
 	}
 	response.OK(c, role)
 }
+
+type bindMemberPhoneReq struct {
+	Phone string `json:"phone" binding:"required"`
+}
+
+// BindCurrentMerchantMemberPhone 商户管理员为当前商户成员绑定/修改登录手机号。
+func (h *MerchantHandler) BindCurrentMerchantMemberPhone(c *gin.Context) {
+	memberID, _ := strconv.ParseUint(c.Param("id"), 10, 64)
+	var req bindMemberPhoneReq
+	if memberID == 0 || c.ShouldBindJSON(&req) != nil {
+		response.BadRequest(c, "请输入手机号")
+		return
+	}
+	user, err := h.merchantSvc.SetMemberPhone(
+		middleware.GetMerchantID(c), uint(memberID), req.Phone, middleware.GetUserID(c),
+	)
+	if err != nil {
+		writeServiceError(c, err, "手机号绑定失败")
+		return
+	}
+	response.OK(c, user)
+}
+
+// ResetCurrentMerchantMemberDevice 重置当前商户成员绑定的 DCAuth 设备。
+func (h *MerchantHandler) ResetCurrentMerchantMemberDevice(c *gin.Context) {
+	memberID, _ := strconv.ParseUint(c.Param("id"), 10, 64)
+	if memberID == 0 {
+		response.BadRequest(c, "参数错误")
+		return
+	}
+	reset, err := h.merchantSvc.ResetMemberDevice(
+		middleware.GetMerchantID(c), uint(memberID), middleware.GetUserID(c),
+	)
+	if err != nil {
+		writeServiceError(c, err, "设备重置失败")
+		return
+	}
+	response.OK(c, gin.H{"reset": reset})
+}