feat: Market Events admin page — source_refs + per-instrument impacts

- DB: colonne source_refs sur market_events (migration idempotente)
- save/update_market_event: persist source_refs (JSON array de {url,title,source})
- market_event_detector: stocke source_refs + évalue impacts instruments après chaque création
- Nouveau router /api/market-events: CRUD + evaluate + impacts CRUD
- Page MarketEvents.tsx: liste filtrée/triée + panneau détail (sources cliquables,
  tableau impacts par instrument avec score/direction/rationale inline-éditables,
  ajout manuel, bulk-evaluate)
- Sidebar: entrée Market Events (Radio icon)

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

backend/services/database.py

@@ -942,6 +942,15 @@ def init_db():
     except Exception:
         pass
 
+    # Idempotent column additions
+    for _col_sql in [
+        "ALTER TABLE market_events ADD COLUMN source_refs TEXT DEFAULT '[]'",
+    ]:
+        try:
+            c.execute(_col_sql)
+        except Exception:
+            pass
+
     conn.commit()
     conn.close()
 
@@ -4545,18 +4554,22 @@ def save_market_event(ev: Dict[str, Any]) -> int:
     import json
     conn = get_conn()
     try:
+        src_refs = ev.get("source_refs", [])
+        if isinstance(src_refs, list):
+            src_refs = json.dumps(src_refs)
         cur = conn.execute("""INSERT INTO market_events
             (name, start_date, end_date, level, category, description, market_impact,
              affected_assets, impact_score, parent_event_id,
-             expected_value, actual_value, surprise_pct, unit, sub_type, absorption_pct)
-            VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)""",
+             expected_value, actual_value, surprise_pct, unit, sub_type, absorption_pct,
+             source_refs)
+            VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)""",
             (ev["name"], ev["start_date"], ev.get("end_date"),
              ev["level"], ev.get("category", "macro"), ev.get("description", ""),
              ev.get("market_impact", ""), json.dumps(ev.get("affected_assets", [])),
              ev.get("impact_score", 0.5), ev.get("parent_event_id"),
              ev.get("expected_value"), ev.get("actual_value"),
              ev.get("surprise_pct"), ev.get("unit"), ev.get("sub_type"),
-             ev.get("absorption_pct")))
+             ev.get("absorption_pct"), src_refs))
         conn.commit()
         return cur.lastrowid
     finally:
@@ -4567,17 +4580,20 @@ def update_market_event(event_id: int, ev: Dict[str, Any]) -> bool:
     import json
     conn = get_conn()
     try:
+        src_refs = ev.get("source_refs", [])
+        if isinstance(src_refs, list):
+            src_refs = json.dumps(src_refs)
         conn.execute("""UPDATE market_events SET
             name=?, start_date=?, end_date=?, level=?, category=?, description=?,
             market_impact=?, affected_assets=?, impact_score=?,
-            absorption_pct=?, relevant_indicators=?
+            absorption_pct=?, relevant_indicators=?, source_refs=?
             WHERE id=?""",
             (ev["name"], ev["start_date"], ev.get("end_date"),
              ev["level"], ev.get("category", "macro"), ev.get("description", ""),
              ev.get("market_impact", ""), json.dumps(ev.get("affected_assets", [])),
              ev.get("impact_score", 0.5),
              ev.get("absorption_pct"), json.dumps(ev.get("relevant_indicators", [])),
-             event_id))
+             src_refs, event_id))
         conn.commit()
         return True
     finally: