feat(channels): 模型定价支持一键同步最新模型

从 LiteLLM 定价目录中读取指定平台的最新模型列表，
将尚未录入的模型以新定价条目（价格留空）的形式追加，
管理员只需点击同步最新模型按钮即可完成操作。

- backend/service: PricingService 新增 ListModelNamesByProvider
- backend/handler: ChannelHandler 新增 SyncPricingModels (GET /api/v1/admin/channels/pricing/sync-models)
- backend/routes: 注册新路由（在 /:id 通配符之前）
- backend/wire_gen: 手动更新 NewChannelHandler 调用
- frontend/api: channels.ts 新增 syncPricingModels
- frontend/i18n: zh.ts / en.ts 新增 5 个 key
- frontend/view: ChannelsView 定价区域标题行新增「同步最新模型」按钮
- tests: pricing_service_test + channel_handler_test 新增单元测试

backend/internal/handler/admin/channel_handler.go

@@ -17,11 +17,12 @@ import (
 type ChannelHandler struct {
 	channelService *service.ChannelService
 	billingService *service.BillingService
+	pricingService *service.PricingService
 }
 
 // NewChannelHandler creates a new admin channel handler
-func NewChannelHandler(channelService *service.ChannelService, billingService *service.BillingService) *ChannelHandler {
-	return &ChannelHandler{channelService: channelService, billingService: billingService}
+func NewChannelHandler(channelService *service.ChannelService, billingService *service.BillingService, pricingService *service.PricingService) *ChannelHandler {
+	return &ChannelHandler{channelService: channelService, billingService: billingService, pricingService: pricingService}
 }
 
 // --- Request / Response types ---
@@ -500,3 +501,34 @@ func (h *ChannelHandler) GetModelDefaultPricing(c *gin.Context) {
 		"image_output_price": pricing.ImageOutputPricePerToken,
 	})
 }
+
+// platformToLiteLLMProvider maps a channel platform name to the corresponding
+// LiteLLM provider string used as the key in the pricing catalog.
+var platformToLiteLLMProvider = map[string]string{
+	service.PlatformAnthropic:   "anthropic",
+	service.PlatformOpenAI:      "openai",
+	service.PlatformGemini:      "google",
+	service.PlatformAntigravity: "anthropic",
+}
+
+// SyncPricingModels 返回 LiteLLM 定价目录中指定平台的最新模型列表
+// GET /api/v1/admin/channels/pricing/sync-models?platform=anthropic
+func (h *ChannelHandler) SyncPricingModels(c *gin.Context) {
+	platform := strings.ToLower(strings.TrimSpace(c.Query("platform")))
+	if platform == "" {
+		response.ErrorFrom(c, infraerrors.BadRequest("MISSING_PARAMETER", "platform parameter is required").
+			WithMetadata(map[string]string{"param": "platform"}))
+		return
+	}
+
+	provider, ok := platformToLiteLLMProvider[platform]
+	if !ok {
+		response.ErrorFrom(c, infraerrors.BadRequest("UNSUPPORTED_PLATFORM",
+			fmt.Sprintf("unsupported platform: %s", platform)).
+			WithMetadata(map[string]string{"param": "platform"}))
+		return
+	}
+
+	models := h.pricingService.ListModelNamesByProvider(provider)
+	response.Success(c, gin.H{"models": models})
+}