feat: Pattern Lab — historical backtest engine for pattern discovery

- Remove all built-in patterns (no proof of legitimacy); seed_builtin_patterns is now a no-op
- DB: add backtest_lab_runs table + backtest_hits/runs_count columns on patterns
- services/pattern_lab.py: build_historical_context (yfinance + RSI/MA200),
  run_ai_backtest (GPT-4o as historical analyst), evaluate_outcomes (actual moves at T+horizon)
- routers/pattern_lab.py: POST /run, POST /evaluate/{id}, GET /runs, DELETE /runs/{id},
  POST /save-pattern (promotes hit pattern to library with reliability counters)
- PatternLab.tsx: 34 preset events 2015-2025 (macro/geo/credit/fx/commodities/volatility/tech),
  3-panel layout — preset selector + wizard + run history, market data table,
  AI pattern cards with hit/miss outcome display, Save to Library button
- useApi.ts: usePatternLabRuns, useRunPatternLab, useEvaluatePatternLab, useSaveLabPattern, useDeleteLabRun
- Sidebar + App.tsx: /pattern-lab route + FlaskConical nav link

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/App.tsx

@@ -10,6 +10,7 @@ import CalendarPage from './pages/CalendarPage'
 import Portfolio from './pages/Portfolio'
 import PatternEditor from './pages/PatternEditor'
 import PatternExplorer from './pages/PatternExplorer'
+import PatternLab from './pages/PatternLab'
 import JournalDeBord from './pages/JournalDeBord'
 import RapportIA from './pages/RapportIA'
 import SuperContexte from './pages/SuperContexte'
@@ -43,6 +44,7 @@ export default function App() {
             <Route path="/options" element={<OptionsLab />} />
             <Route path="/patterns" element={<PatternExplorer />} />
             <Route path="/patterns/edit" element={<PatternEditor />} />
+            <Route path="/pattern-lab" element={<PatternLab />} />
             <Route path="/portfolio" element={<Portfolio />} />
             <Route path="/backtest" element={<Backtest />} />
             <Route path="/calendar" element={<CalendarPage />} />