C5: Remove duplicate entry_fee deduction in backtester (balance and net_pnl)
C1: Add SL/TP retry (3x) with emergency market close on final failure
C3: Add _close_lock to prevent PnL double recording between callback and monitor
C8: Add SIGTERM/SIGINT handler with per-symbol order cancellation before exit
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
