Add Binance SIM market adapter and exchange switch in settings.

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

backend/app/strategy/selection.py

@@ -25,7 +25,7 @@ def hours_until_expiry(
     if expiry_ms is not None:
         return hours_until_ms(expiry_ms, now)
     # 兼容测试：无 ms 时按 OKX 惯例（UTC 08:00）推算
-    from ..exchange.okx.parse import expiry_ms_from_ymd
+    from ..exchange.expiry import expiry_ms_from_ymd
 
     return hours_until_ms(expiry_ms_from_ymd(ymd), now)
 
@@ -76,7 +76,7 @@ def _complete_by_expiry(
         if ymd in ms_map:
             ems = ms_map[ymd]
         else:
-            from ..exchange.okx.parse import expiry_ms_from_ymd
+            from ..exchange.expiry import expiry_ms_from_ymd
 
             ems = expiry_ms_from_ymd(ymd)
         out[ymd] = (ems, complete)