feat: support claude convert to gemini

model/channel_cache.go

@@ -130,7 +130,7 @@ func getRandomSatisfiedChannel(group string, model string, retry int) (*Channel,
 	channels := group2model2channels[group][model]
 
 	if len(channels) == 0 {
-		return nil, errors.New("channel not found")
+		return nil, nil
 	}
 
 	if len(channels) == 1 {