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/gemini/gemini/gemini_gemini_response.go

@@ -9,8 +9,6 @@ import (
 
 // PassthroughGeminiResponseStream forwards Gemini responses unchanged.
 func PassthroughGeminiResponseStream(_ context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) []string {
-	log.Debug("PassthroughGeminiResponseStream")
-
 	if bytes.HasPrefix(rawJSON, []byte("data:")) {
 		rawJSON = bytes.TrimSpace(rawJSON[5:])
 	}
@@ -24,6 +22,5 @@ func PassthroughGeminiResponseStream(_ context.Context, _ string, originalReques
 
 // PassthroughGeminiResponseNonStream forwards Gemini responses unchanged.
 func PassthroughGeminiResponseNonStream(_ context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) string {
-	log.Debug("PassthroughGeminiResponseNonStream")
 	return string(rawJSON)
 }