fix: ccxt Gate 类名 gateio 改为兼容 gate

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/exchange/gate_ccxt_lib.py

@@ -0,0 +1,9 @@
+"""Gate.io ccxt 构造（ccxt 4.x 起类名由 gateio 改为 gate）。"""
+from __future__ import annotations
+
+import ccxt
+
+
+def gate_ccxt_class():
+    """返回 ccxt Gate 交易所类（兼容旧版 gateio 名称）。"""
+    return getattr(ccxt, "gate", None) or ccxt.gateio