feat(matcher): 集合竞价CALL_AUCTION撮合(分期项)—开盘价(最大成交量原则→open)

CALL_AUCTION枚举原拒单(unsupported), 现撮合用开盘价(open, 集合竞价确定开盘价).
当前定价同NEXT_OPEN(均为open); 未来区分开盘/尾盘集合竞价需扩枚举.
test: call_auction fills@open(原rejected用例改).

sanguo_trader/matcher.py

@@ -72,6 +72,10 @@ def cross_order(
         fill_price = float(match_bar["open"])
     elif order.match_session == MatchSession.CURRENT_CLOSE:
         fill_price = float(match_bar["close"])
+    elif order.match_session == MatchSession.CALL_AUCTION:
+        # 集合竞价开盘价（最大成交量原则 → open）。当前同 NEXT_OPEN 定价；
+        # 未来区分开盘/尾盘集合竞价需扩枚举（CALL_AUCTION_OPEN/CLOSE）。
+        fill_price = float(match_bar["open"])
     else:
         return PaperReject(
             order.strategy_id, symbol, "unsupported_match_session", bar_date