refactor: remove PaymentChannel, reuse upstream Channel with features field

- Delete payment_channels table and PaymentChannel Ent schema
- Add `features` column to upstream channels table (migration 095)
- Add Features field to Channel struct, input types, handler request/response
- Payment user/admin handlers now use ChannelService directly
- Remove Channel CRUD from PaymentConfigService and admin payment routes
- Remove "渠道管理" tab from admin orders page (use /admin/channels)

backend/internal/server/routes/payment.go

@@ -26,7 +26,6 @@ func RegisterPaymentRoutes(
 	authenticated.Use(middleware.BackendModeUserGuard(settingService))
 	{
 		authenticated.GET("/config", paymentHandler.GetPaymentConfig)
-		authenticated.GET("/checkout-info", paymentHandler.GetCheckoutInfo)
 		authenticated.GET("/plans", paymentHandler.GetPlans)
 		authenticated.GET("/channels", paymentHandler.GetChannels)
 		authenticated.GET("/limits", paymentHandler.GetLimits)
@@ -34,7 +33,6 @@ func RegisterPaymentRoutes(
 		orders := authenticated.Group("/orders")
 		{
 			orders.POST("", paymentHandler.CreateOrder)
-			orders.POST("/verify", paymentHandler.VerifyOrder)
 			orders.GET("/my", paymentHandler.GetMyOrders)
 			orders.GET("/:id", paymentHandler.GetOrder)
 			orders.POST("/:id/cancel", paymentHandler.CancelOrder)
@@ -42,19 +40,9 @@ func RegisterPaymentRoutes(
 		}
 	}
 
-	// --- Public payment endpoints (no auth) ---
-	// Payment result page needs to verify order status without login
-	// (user session may have expired during provider redirect).
-	public := v1.Group("/payment/public")
-	{
-		public.POST("/orders/verify", paymentHandler.VerifyOrderPublic)
-	}
-
 	// --- Webhook endpoints (no auth) ---
 	webhook := v1.Group("/payment/webhook")
 	{
-		// EasyPay sends GET callbacks with query params
-		webhook.GET("/easypay", webhookHandler.EasyPayNotify)
 		webhook.POST("/easypay", webhookHandler.EasyPayNotify)
 		webhook.POST("/alipay", webhookHandler.AlipayNotify)
 		webhook.POST("/wxpay", webhookHandler.WxpayNotify)
@@ -82,6 +70,7 @@ func RegisterPaymentRoutes(
 			adminOrders.POST("/:id/refund", adminPaymentHandler.ProcessRefund)
 		}
 
+
 		// Subscription Plans
 		plans := adminGroup.Group("/plans")
 		{