Support per-symbol strategy parameters (ATR_SL_MULT_XRPUSDT, etc.) via env vars, falling back to global defaults. Sweep results: - XRPUSDT: SL=1.5 TP=4.0 ADX=30 (PF 2.39, Sharpe 61.0) - TRXUSDT: SL=1.0 TP=4.0 ADX=30 (PF 3.87, Sharpe 62.8) - DOGEUSDT: SL=2.0 TP=2.0 ADX=30 (PF 1.80, Sharpe 44.1) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>