Add Codex load balancing documentation and refine JSON handling logic

- Updated README and README_CN to include a guide for configuring multiple account load balancing with CLI Proxy API.
- Enhanced JSON handling in gemini translators by differentiating object and string outputs.
- Added commented debug logging for Gemini CLI response conversion.

internal/translator/gemini-cli/openai/responses/cli_openai-responses_request.go

@@ -10,5 +10,6 @@ import (
 func ConvertOpenAIResponsesRequestToGeminiCLI(modelName string, inputRawJSON []byte, stream bool) []byte {
 	rawJSON := bytes.Clone(inputRawJSON)
 	rawJSON = ConvertOpenAIResponsesRequestToGemini(modelName, rawJSON, stream)
+	// log.Debug(string(rawJSON))
 	return ConvertGeminiRequestToGeminiCLI(modelName, rawJSON, stream)
 }