feat: implement new handlers for audio, image, embedding, and responses processing

- Added new handlers: AudioHelper, ImageHelper, EmbeddingHelper, and ResponsesHelper to manage respective requests.
- Updated ModelMappedHelper to accept request parameters for better model mapping.
- Enhanced error handling and validation across new handlers to ensure robust request processing.
- Introduced support for new relay formats in relay_info and updated relevant functions accordingly.

relay/channel/gemini/adaptor.go

@@ -73,12 +73,12 @@ func (a *Adaptor) GetRequestURL(info *relaycommon.RelayInfo) (string, error) {
 
 	if model_setting.GetGeminiSettings().ThinkingAdapterEnabled {
 		// 新增逻辑：处理 -thinking-<budget> 格式
-		if strings.Contains(info.OriginModelName, "-thinking-") {
+		if strings.Contains(info.UpstreamModelName, "-thinking-") {
 			parts := strings.Split(info.UpstreamModelName, "-thinking-")
 			info.UpstreamModelName = parts[0]
-		} else if strings.HasSuffix(info.OriginModelName, "-thinking") { // 旧的适配
+		} else if strings.HasSuffix(info.UpstreamModelName, "-thinking") { // 旧的适配
 			info.UpstreamModelName = strings.TrimSuffix(info.UpstreamModelName, "-thinking")
-		} else if strings.HasSuffix(info.OriginModelName, "-nothinking") {
+		} else if strings.HasSuffix(info.UpstreamModelName, "-nothinking") {
 			info.UpstreamModelName = strings.TrimSuffix(info.UpstreamModelName, "-nothinking")
 		}
 	}

relay/channel/gemini/relay-gemini.go

@@ -99,7 +99,7 @@ func CovertGemini2OpenAI(textRequest dto.GeneralOpenAIRequest, info *relaycommon
 	}
 
 	if model_setting.GetGeminiSettings().ThinkingAdapterEnabled {
-		modelName := info.OriginModelName
+		modelName := info.UpstreamModelName
 		isNew25Pro := strings.HasPrefix(modelName, "gemini-2.5-pro") &&
 			!strings.HasPrefix(modelName, "gemini-2.5-pro-preview-05-06") &&
 			!strings.HasPrefix(modelName, "gemini-2.5-pro-preview-03-25")