fix: 删除STBL, 撤回22002错误修正（22002是Passphrase认证问题）

- 删除 scanner.go 中的 STBL
- 撤回 22002 的'已平仓'处理（该码是API认证错误）
- 保持 closeLeg 报错原样输出

scanner.go

@@ -156,7 +156,6 @@ var TrackedCoins = []TrackedCoin{
 	{Name: "SOPH", BN: "", BG: "SOPHUSDT", HL: "SOPH"},
 	{Name: "SPX", BN: "", BG: "SPXUSDT", HL: "SPX"},
 	{Name: "STABLE", BN: "", BG: "STABLEUSDT", HL: "STABLE"},
-	{Name: "STBL", BN: "", BG: "STBLUSDT", HL: "STBL"},
 	{Name: "STG", BN: "", BG: "STGUSDT", HL: ""},
 	{Name: "STRK", BN: "", BG: "STRKUSDT", HL: "STRK"},
 	{Name: "STX", BN: "", BG: "STXUSDT", HL: "STX"},

trader.go

@@ -1404,7 +1404,7 @@ func (t *Trader) closeLeg(leg *PositionLeg) string {
 		}
 		resp, err := t.bitget.PlaceMarketOrder(side, leg.Coin+"USDT", leg.Size, "close", holdSide)
 		if err != nil {
-			return fmt.Sprintf("%v", err)
+			return fmt.Sprintf("BG close 22002: %v", err)
 		}
 		log.Printf("[ExRes] BG close %s %s: size=%s → response=%s", side, leg.Coin+"USDT", leg.Size, resp)
 	} else {