fix: remove leaked models + add honest data/backtest tooling

- Delete all old XGBoost/HMM models trained with the order-block look-ahead
  leak (models/backups/* + root models). They reproduced a fake 63.9% WR /
  2.64 PF that collapses to ~35% WR / 0.95 PF once the leak is fixed.
- scripts/collect_data.py: dedicated raw M1+M15 collector (paginated)
- scripts/fast_backtest.py: vectorized GPU backtest for honest validation
- backtest_live_sync.py: read SYMBOL from env (XM uses GOLD, not XAUUSD)
- stop tracking generated data/training_data.parquet

See upstream report: GifariKemal/xaubot-ai#4

backtests/backtest_live_sync.py

@@ -884,7 +884,9 @@ def main():
 
     # Fetch maximum historical data
     print("Fetching historical data...")
-    df = mt5.get_market_data(symbol="XAUUSD", timeframe="M15", count=50000)
+    import os
+    _symbol = os.getenv("SYMBOL", "XAUUSD")
+    df = mt5.get_market_data(symbol=_symbol, timeframe="M15", count=50000)
 
     if len(df) == 0:
         print("ERROR: No data received")