fix: 工具调用 arguments 为空时保留 tool_use 块 (#5543)

relay/channel/claude/relay-claude.go

@@ -410,9 +410,10 @@ func RequestOpenAI2ClaudeMessage(c *gin.Context, textRequest dto.GeneralOpenAIRe
 				if message.ToolCalls != nil {
 					for _, toolCall := range message.ParseToolCalls() {
 						inputObj := make(map[string]any)
-						if err := json.Unmarshal([]byte(toolCall.Function.Arguments), &inputObj); err != nil {
+						if args := toolCall.Function.Arguments; args != "" {
+							if err := json.Unmarshal([]byte(args), &inputObj); err != nil {
 								common.SysLog("tool call function arguments is not a map[string]any: " + fmt.Sprintf("%v", toolCall.Function.Arguments))
-							continue
+							}
 						}
 						claudeMediaMessages = append(claudeMediaMessages, dto.ClaudeMediaMessage{
 							Type:  "tool_use",