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>

frontend/src/App.tsx

@@ -7,6 +7,7 @@ import WatchlistPage from './pages/WatchlistPage';
 import TickerDetailPage from './pages/TickerDetailPage';
 import ScannerPage from './pages/ScannerPage';
 import RankingsPage from './pages/RankingsPage';
+import PerformancePage from './pages/PerformancePage';
 import AdminPage from './pages/AdminPage';
 
 export default function App() {
@@ -21,6 +22,7 @@ export default function App() {
           <Route path="/ticker/:symbol" element={<TickerDetailPage />} />
           <Route path="/scanner" element={<ScannerPage />} />
           <Route path="/rankings" element={<RankingsPage />} />
+          <Route path="/performance" element={<PerformancePage />} />
           <Route element={<ProtectedRoute requireAdmin />}>
             <Route path="/admin" element={<AdminPage />} />
           </Route>