增加排序

backend/app/exceptions.py

@@ -0,0 +1,7 @@
+class BinanceRateLimitedError(Exception):
+    """币安 418/429，IP 临时封禁。"""
+
+    def __init__(self, retry_after_sec: int, path: str = ""):
+        self.retry_after_sec = retry_after_sec
+        self.path = path
+        super().__init__(f"rate limited {retry_after_sec}s on {path}")