feat: Timeline Navigator — contexte historique 3 temporalités COVID → aujourd'hui

- 2 nouvelles tables SQLite : market_events + timeline_context
- 32 événements historiques seedés (long/medium/short de feb 2020 à juin 2026)
- timeline_service.py : bootstrap, get_events_for_date, génération commentaires GPT-4o-mini
- /api/timeline router : GET /day/{date}, GET /events, POST /generate/{date}, POST /bootstrap
- Timeline.tsx : navigateur date avec strip visuel, 3 panneaux contextuels, catalogue d'événements
- Sidebar : entrée Timeline avec icône Layers

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

backend/main.py

@@ -3,6 +3,7 @@ from fastapi.middleware.cors import CORSMiddleware
 from routers import market_data, geopolitical, options, backtest, ai, portfolio, config, patterns, journal, cycle as cycle_router, profiles as profiles_router, reasoning as reasoning_router, knowledge as knowledge_router, options_vol as options_vol_router, analytics as analytics_router, risk as risk_router
 from routers import pattern_lab as pattern_lab_router
 from routers import specialist_desks as specialist_desks_router
+from routers import timeline as timeline_router
 from routers import logs as logs_router
 from routers import var as var_router
 from routers import reports as reports_router
@@ -121,6 +122,7 @@ app.include_router(reports_router.router)
 app.include_router(institutional_router.router)
 app.include_router(pattern_lab_router.router)
 app.include_router(specialist_desks_router.router)
+app.include_router(timeline_router.router)
 
 
 @app.get("/")