Suppress debug logs for model routing and ignore empty tools arrays

- Comment out verbose routing logs in the API server to reduce noise.
- Remove the `tools` field from Qwen client requests when it is an empty array.
- Add guards in Claude, Codex, Gemini‑CLI, and Gemini translators to skip tool conversion when the `tools` array is empty, preventing unnecessary payload modifications.

internal/translator/codex/openai/codex_openai_request.go

@@ -231,7 +231,7 @@ func ConvertOpenAIRequestToCodex(modelName string, rawJSON []byte, stream bool)
 
 	// Map tools (flatten function fields)
 	tools := gjson.GetBytes(rawJSON, "tools")
-	if tools.IsArray() {
+	if tools.IsArray() && len(tools.Array()) > 0 {
 		out, _ = sjson.SetRaw(out, "tools", `[]`)
 		arr := tools.Array()
 		for i := 0; i < len(arr); i++ {