fix: 최종 회의 CRITICAL 1건 + MEDIUM 2건 수정

1. swing/scheduler: mdd_manager.update() 매 사이클 호출 추가
   — 새 스케줄러에서 MDD -10%/-20% 감지가 완전 무력화되어 있었음
2. mdd_manager: place_order() → safe_place_order() 변경
   — 세마포어+분산락 보호로 이중 매도 방지
3. mdd_manager: 매도 후 ActiveTrade close/update 추가
   — 전량 매도 시 enqueue_close_active_trade()
   — 부분 매도 시 remaining_pct 갱신

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/mdd_manager.py

@@ -230,7 +230,8 @@ class MDDManager:
                 sell_qty = min(sell_qty, quantity)
 
                 try:
-                    order_resp = await korea_investment_api.place_order(
+                    from app.services.trade_executor import safe_place_order
+                    order_resp = await safe_place_order(
                         stock_code=stock_code,
                         order_type="SELL",
                         quantity=sell_qty,
@@ -269,6 +270,20 @@ class MDDManager:
                             "strategy_type": "mdd_reduction",
                         })
 
+                        # [FIX] 전량 매도 시 ActiveTrade 닫기
+                        remaining_qty = quantity - sell_qty
+                        if remaining_qty <= 0:
+                            from app.services.db_worker import enqueue_close_active_trade
+                            await enqueue_close_active_trade(stock_code)
+                        else:
+                            # 부분 매도: remaining_pct 갱신
+                            from app.services.db_worker import enqueue_active_trade_upsert
+                            new_remaining = remaining_qty / quantity
+                            await enqueue_active_trade_upsert({
+                                "stock_code": stock_code,
+                                "remaining_pct": new_remaining,
+                            })
+
                         results.append({
                             "stock_code": stock_code,
                             "stock_name": stock_name,