feat: add actor user column to events and dashboard tables

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/event_summary.py

@@ -1,5 +1,6 @@
 from app.models.event import Event
 from app.schemas.list_models import EventSummary
+from app.services.event_actor_user import extract_event_actor_user
 
 
 def event_to_summary(event: Event) -> EventSummary:
@@ -18,4 +19,5 @@ def event_to_summary(event: Event) -> EventSummary:
         severity=event.severity,
         title=event.title,
         summary=event.summary,
+        actor_user=extract_event_actor_user(event.type, event.details),
     )