Add 11 financial fields (sharpe, sortino, win_rate, max_drawdown, profit_factor, total_return, avg_return, total_trades, action distribution) to TrainingSession (fields 36-46), a new GetEpochHistory RPC with request/response messages, and wire the Prometheus metric mapping in the monitoring service with a stub RPC handler for task 7. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>