fix(escalations): add sidebar badge count + show all team escalations

- Add escalation_count to sidebar stats (team-wide requesting_escalation)
- Show badge on Escalations nav item in sidebar
- Remove user_id filter from escalation queue — show all team escalations
  including your own (needed for solo users and visibility)

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

backend/app/api/endpoints/ai_sessions.py

@@ -415,7 +415,6 @@ async def get_escalation_queue(
         .where(
             AISession.team_id == current_user.team_id,
             AISession.status == "requesting_escalation",
-            AISession.user_id != current_user.id,  # Don't show own escalated sessions
         )
         .order_by(AISession.created_at.desc())
     )