fix(channels): support kimi/zhipu/deepseek platforms in channel pricing

- ChannelsView platformOrder now includes the three CN provider
  platforms so channel pricing can be configured for them; composite
  group expansion/attachment stays limited to the five main platforms
  (matches backend isConcreteRequestPlatform and composite-routes
  target_platform validation)
- SyncPricingModels maps kimi->moonshot, zhipu->zhipu,
  deepseek->deepseek; also fixes gemini mapping to "google" which
  matched zero catalog entries (provider key is "gemini")
- Add CN platform colors to channel pricing model tag classes

backend/internal/handler/admin/channel_handler.go

@@ -568,9 +568,12 @@ func (h *ChannelHandler) GetModelDefaultPricing(c *gin.Context) {
 var platformToLiteLLMProvider = map[string]string{
 	service.PlatformAnthropic:   "anthropic",
 	service.PlatformOpenAI:      "openai",
-	service.PlatformGemini:      "google",
+	service.PlatformGemini:      "gemini",
 	service.PlatformAntigravity: "anthropic",
 	service.PlatformGrok:        "xai",
+	service.PlatformKimi:        "moonshot",
+	service.PlatformZhipu:       "zhipu",
+	service.PlatformDeepseek:    "deepseek",
 }
 
 // SyncPricingModels 返回 LiteLLM 定价目录中指定平台的最新模型列表

backend/internal/handler/admin/channel_handler_test.go

@@ -502,7 +502,7 @@ func TestSyncPricingModels_ValidPlatform_EmptyService(t *testing.T) {
 	svc := service.NewPricingService(nil, nil)
 	router := setupSyncPricingModelsRouter(svc)
 
-	for _, platform := range []string{"anthropic", "openai", "gemini", "antigravity"} {
+	for _, platform := range []string{"anthropic", "openai", "gemini", "antigravity", "grok", "kimi", "zhipu", "deepseek"} {
 		req := httptest.NewRequest(http.MethodGet, "/channels/pricing/sync-models?platform="+platform, nil)
 		w := httptest.NewRecorder()
 		router.ServeHTTP(w, req)