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/claude/openai/claude_openai_request.go

@@ -244,7 +244,7 @@ func ConvertOpenAIRequestToClaude(modelName string, rawJSON []byte, stream bool)
 	}
 
 	// Tools mapping: OpenAI tools -> Claude Code tools
-	if tools := root.Get("tools"); tools.Exists() && tools.IsArray() {
+	if tools := root.Get("tools"); tools.Exists() && tools.IsArray() && len(tools.Array()) > 0 {
 		var anthropicTools []interface{}
 		tools.ForEach(func(_, tool gjson.Result) bool {
 			if tool.Get("type").String() == "function" {

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++ {

internal/translator/gemini-cli/openai/cli_openai_request.go

@@ -215,7 +215,7 @@ func ConvertOpenAIRequestToGeminiCLI(modelName string, rawJSON []byte, _ bool) [
 
 	// tools -> request.tools[0].functionDeclarations
 	tools := gjson.GetBytes(rawJSON, "tools")
-	if tools.IsArray() {
+	if tools.IsArray() && len(tools.Array()) > 0 {
 		out, _ = sjson.SetRawBytes(out, "request.tools", []byte(`[{"functionDeclarations":[]}]`))
 		fdPath := "request.tools.0.functionDeclarations"
 		for _, t := range tools.Array() {

internal/translator/gemini/openai/gemini_openai_request.go

@@ -215,7 +215,7 @@ func ConvertOpenAIRequestToGemini(modelName string, rawJSON []byte, _ bool) []by
 
 	// tools -> tools[0].functionDeclarations
 	tools := gjson.GetBytes(rawJSON, "tools")
-	if tools.IsArray() {
+	if tools.IsArray() && len(tools.Array()) > 0 {
 		out, _ = sjson.SetRawBytes(out, "tools", []byte(`[{"functionDeclarations":[]}]`))
 		fdPath := "tools.0.functionDeclarations"
 		for _, t := range tools.Array() {