feat: origin tracing on all market_events

- DB: colonne origin (migration + UPDATE heuristique sur données legacy)
- save/update_market_event: persist origin
- Tous les points de création taguent leur origine:
    bootstrap_macro/eco/ma/legacy | detector_news/eco/technical/report | manual
- UI MarketEvents: badge d'origine avec icône + description dans le panneau détail,
  icône tooltip dans la liste gauche, message explicite si pas de source_refs

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

backend/routers/market_events.py

@@ -139,6 +139,7 @@ def create_event(body: EventCreate) -> Dict[str, Any]:
     from services.database import save_market_event
     data = body.dict()
     data["source_refs"] = [r.dict() for r in body.source_refs]
+    data.setdefault("origin", "manual")
     new_id = save_market_event(data)
     return {"id": new_id, "status": "created"}
 

backend/routers/timeline.py

@@ -43,7 +43,9 @@ def list_events() -> List[Dict[str, Any]]:
 @router.post("/events")
 def create_event(body: EventCreate) -> Dict[str, Any]:
     from services.database import save_market_event
-    new_id = save_market_event(body.dict())
+    data = body.dict()
+    data.setdefault("origin", "manual")
+    new_id = save_market_event(data)
     return {"id": new_id, "status": "created"}