feat: Add Baidu Qianfan V2 channel support #725

- Update channel constants to include Baidu V2 channel
- Create new Baidu V2 adaptor for relay
- Add Baidu V2 models and channel configuration
- Update relay adaptor to support Baidu V2 channel
- Modify web channel constants to include Baidu V2 option

relay/constant/api_type.go

@@ -29,6 +29,7 @@ const (
 	APITypeDeepSeek
 	APITypeMokaAI
 	APITypeVolcEngine
+	APITypeBaiduV2
 	APITypeDummy // this one is only for count, do not add any channel after this
 )
 
@@ -83,6 +84,8 @@ func ChannelType2APIType(channelType int) (int, bool) {
 		apiType = APITypeMokaAI
 	case common.ChannelTypeVolcEngine:
 		apiType = APITypeVolcEngine
+	case common.ChannelTypeBaiduV2:
+		apiType = APITypeBaiduV2
 	}
 	if apiType == -1 {
 		return APITypeOpenAI, false