feat: show RDP session duration in Overview and Events (0.5.16)

Add session_duration_sec to EventSummary and a Duration column (HH:MM:SS / Nd HH:MM:SS).

backend/app/services/event_summary.py

@@ -6,6 +6,7 @@ from app.services.event_actor_user import extract_event_actor_user
 from app.services.host_sessions import event_session_terminated
 from app.services.rdg_display import build_rdg_display
 from app.services.rdg_session_flap import resolve_rdg_flap_summary
+from app.services.session_duration import extract_session_duration_sec
 
 
 def event_to_summary(event: Event, db: Session | None = None) -> EventSummary:
@@ -44,6 +45,9 @@ def event_to_summary(event: Event, db: Session | None = None) -> EventSummary:
         title=title,
         summary=summary,
         actor_user=extract_event_actor_user(event.type, event.details),
+        session_duration_sec=extract_session_duration_sec(
+            event.details if isinstance(event.details, dict) else None
+        ),
         rdg_flap=rdg_flap,
         rdg_flap_pair_event_id=rdg_flap_pair_event_id,
         rdg_flap_qwinsta_event_id=rdg_flap_qwinsta_event_id,