Add trade setup outcome tracking and performance stats

Closes the feedback loop on R:R scanner signals:

- Nightly outcome_evaluator job replays unresolved setups against daily
  OHLCV bars: target_hit / stop_hit / ambiguous (same-bar, counted as
  loss) / expired after OUTCOME_EVALUATION_MAX_BARS (default 30)
- Migration 004: evaluated_at + outcome_date on trade_setups
- GET /trades/performance: hit rate, expectancy (avg R), total R with
  breakdowns by direction, recommended action, and confidence bucket
- New Performance page (stat cards, breakdown tables, Evaluate Now,
  methodology disclosure) wired into sidebar and mobile nav
- 17 new unit tests for evaluation logic and stats aggregation

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.env.example

@@ -39,6 +39,10 @@ FUNDAMENTAL_RATE_LIMIT_BACKOFF_SECONDS=15
 DEFAULT_WATCHLIST_AUTO_SIZE=10
 DEFAULT_RR_THRESHOLD=3.0
 
+# Outcome Evaluation
+# Trading days before an undecided setup expires at 0R
+OUTCOME_EVALUATION_MAX_BARS=30
+
 # Database Pool
 DB_POOL_SIZE=5
 DB_POOL_TIMEOUT=30