feat: Enhance GeminiChatHandler to include RelayInfo

- Updated the GeminiChatHandler function to accept an additional parameter, RelayInfo, allowing for better context handling during chat operations.
- Modified the DoResponse method in the Adaptor to pass RelayInfo to GeminiChatHandler, ensuring consistent usage of upstream model information.
- Enhanced the GeminiChatStreamHandler to utilize the upstream model name from RelayInfo, improving response accuracy and data representation in Gemini requests.

relay/channel/gemini/adaptor.go

@@ -76,7 +76,7 @@ func (a *Adaptor) DoResponse(c *gin.Context, resp *http.Response, info *relaycom
 	if info.IsStream {
 		err, usage = GeminiChatStreamHandler(c, resp, info)
 	} else {
-		err, usage = GeminiChatHandler(c, resp)
+		err, usage = GeminiChatHandler(c, resp, info)
 	}
 	return
 }