fix: remove HL-delisted coins from scanner (BNT/CATI/CYBER/ILV/LISTA/OGN/STG) + PIXEL

Root cause: HL WS uses allMids (all coins), BG WS subscribes per-coin.
Delisted coins had stale HL prices showing huge fake spreads (~200%).
Monitor tried entry → BG buy succeeds, HL sell fails (Trading is halted)
→ orphan position on BG accumulated across restarts.

Fix:
- Set HL="" for BNT, CATI, CYBER, ILV, LISTA, OGN, STG, PIXEL
- Add guard in ScanBGHL to skip coins where BG or HL is empty
- Same guard in SpreadWindowTracker.Tick

config.json

@@ -8,7 +8,7 @@
   "trade_cooldown_ms": 30000,
   "alert_cooldown_sec": 300,
   "mock_slippage_pct": 0.05,
-  "max_positions": 5,
+  "max_positions": 1,
   "blacklist_duration_sec": 3600,
   "initial_capital": 1000,
   "taker_fee_bitget": 0.060,