fix(backend): 架构质量改进批次二 (#32-37)

- #32 License 激活迁移到 license_devices 表：Activate/Verify/Deactivate 全部改用
  license_devices，新增 max_devices 校验和 GET /license/devices 端点；
  Activate 现在校验 shop_id 防跨租户激活
- #33 checkInventory 从 StockOutHandler 移到 StockService.CheckInventoryAvailability
- #34 新增 util/response.go 统一错误响应工具（RespondError/RespondSuccess/RespondCreated）
- #35 生产模式 CORS Origin='*' 启动时 Fatal
- #36 生产模式 License 私钥未配置启动时 Fatal
- #37 新增 util/page.go ValidatePageSize，应用到 partner/product/stock_in/stock_out handler

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/internal/handler/license.go

@@ -18,16 +18,19 @@ func NewLicenseHandler(svc *service.LicenseService) *LicenseHandler {
 
 // Activate POST /api/v1/license/activate
 func (h *LicenseHandler) Activate(c *gin.Context) {
+	shopID := middleware.GetShopID(c)
 	var req struct {
 		LicenseKey string `json:"license_key" binding:"required"`
 		DeviceID   string `json:"device_id" binding:"required"`
+		DeviceName string `json:"device_name"`
+		Platform   string `json:"platform"`
 	}
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
 
-	lic, err := h.svc.Activate(req.LicenseKey, req.DeviceID)
+	lic, err := h.svc.Activate(shopID, req.LicenseKey, req.DeviceID, req.DeviceName, req.Platform)
 	if err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
@@ -52,7 +55,7 @@ func (h *LicenseHandler) Verify(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"data": lic})
 }
 
-// Info GET /api/v1/license/info — 当前门店授权概况（无需 device_id）
+// Info GET /api/v1/license/info — 当前门店授权概况
 func (h *LicenseHandler) Info(c *gin.Context) {
 	shopID := middleware.GetShopID(c)
 	lic, err := h.svc.ShopInfo(shopID)
@@ -60,17 +63,35 @@ func (h *LicenseHandler) Info(c *gin.Context) {
 		c.JSON(http.StatusOK, gin.H{"data": nil})
 		return
 	}
+
+	var deviceCount int64
+	// count active devices for this shop
+	devs, _ := h.svc.ListDevices(shopID)
+	deviceCount = int64(len(devs))
+
 	phase := middleware.CalcLicensePhase(lic.ExpiresAt)
 	c.JSON(http.StatusOK, gin.H{"data": gin.H{
-		"id":          lic.ID,
-		"type":        lic.Type,
-		"is_active":   lic.IsActive,
-		"max_devices": lic.MaxDevices,
-		"expires_at":  lic.ExpiresAt,
-		"phase":       phase,
+		"id":           lic.ID,
+		"type":         lic.Type,
+		"is_active":    lic.IsActive,
+		"max_devices":  lic.MaxDevices,
+		"device_count": deviceCount,
+		"expires_at":   lic.ExpiresAt,
+		"phase":        phase,
 	}})
 }
 
+// Devices GET /api/v1/license/devices — 已绑定设备列表
+func (h *LicenseHandler) Devices(c *gin.Context) {
+	shopID := middleware.GetShopID(c)
+	devs, err := h.svc.ListDevices(shopID)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"data": devs})
+}
+
 // Deactivate POST /api/v1/license/deactivate
 func (h *LicenseHandler) Deactivate(c *gin.Context) {
 	shopID := middleware.GetShopID(c)