fix: 重启时查交易所验证持仓是否存在，幽灵仓位自动标记 closed

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

trader.go

@@ -1977,6 +1977,21 @@ func (t *Trader) restoreOpenPositions() {
 			}
 		}
 		pos.DBTradeID = tr.ID
+
+		// Verify position still exists on exchange — if not, mark as closed
+		posMissing := false
+		if t.bitget != nil && (pos.LongLeg.Exchange == ExBitget || pos.ShortLeg.Exchange == ExBitget) {
+			bgSymbol := tr.Coin + "USDT"
+			if bgSize, _ := t.bitget.CheckPosition(bgSymbol); bgSize <= 0 {
+				log.Printf("[Trader] Trade %d (%s): Bitget position not found on exchange, marking as closed", tr.ID, tr.Coin)
+				posMissing = true
+			}
+		}
+		if posMissing {
+			t.db.SetTradeStatus(tr.ID, "closed")
+			continue
+		}
+
 		t.positions[tr.Coin] = pos
 		// Prevent immediate re-trading of the same coin
 		t.lastTradeTime[tr.Coin] = tr.OpenedAt