feat: introduce custom provider example and remove redundant debug logs

- Added `examples/custom-provider/main.go` showcasing custom executor and translator integration using the SDK.
- Removed redundant debug logs from translator modules to enhance code cleanliness.
- Updated SDK documentation with new usage and advanced examples.
- Expanded the management API with new endpoints, including request logging and GPT-5 Codex features.

internal/translator/openai/gemini/openai_gemini_request.go

@@ -21,7 +21,6 @@ import (
 // It extracts the model name, generation config, message contents, and tool declarations
 // from the raw JSON request and returns them in the format expected by the OpenAI API.
 func ConvertGeminiRequestToOpenAI(modelName string, inputRawJSON []byte, stream bool) []byte {
-	log.Debug("ConvertGeminiRequestToOpenAI")
 	rawJSON := bytes.Clone(inputRawJSON)
 	// Base OpenAI Chat Completions API template
 	out := `{"model":"","messages":[]}`