让Mock流水查询复用logId主体账号绑定

lsfx-mock-server/services/file_service.py

@@ -67,6 +67,10 @@ class FileService:
         self.file_records: Dict[int, FileRecord] = {}  # logId -> FileRecord
         self.log_counter = settings.INITIAL_LOG_ID
 
+    def get_file_record(self, log_id: int) -> FileRecord:
+        """按 logId 获取已存在的文件记录。"""
+        return self.file_records.get(log_id)
+
     def _infer_bank_name(self, filename: str) -> tuple:
         """根据文件名推断银行名称和模板名称"""
         if "支付宝" in filename or "alipay" in filename.lower():