fix(escalations): fall back to account_id when team_id is null

Users without team_id (solo accounts, pro plans) couldn't see
escalations because the query filtered by team_id which was NULL.
Now falls back to account_id scoping for both the escalation queue
endpoint and the sidebar badge count.

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

backend/app/api/endpoints/ai_sessions.py

@@ -406,14 +406,19 @@ async def get_escalation_queue(
     db: Annotated[AsyncSession, Depends(get_db)],
     _: None = Depends(require_engineer_or_admin),
 ):
-    """List sessions requesting escalation for the current user's team."""
-    if not current_user.team_id:
+    """List sessions requesting escalation for the current user's team/account."""
+    # Match by team_id if available, otherwise fall back to account_id
+    if current_user.team_id:
+        scope_filter = AISession.team_id == current_user.team_id
+    elif current_user.account_id:
+        scope_filter = AISession.account_id == current_user.account_id
+    else:
         return []
 
     result = await db.execute(
         select(AISession)
         .where(
-            AISession.team_id == current_user.team_id,
+            scope_filter,
             AISession.status == "requesting_escalation",
         )
         .order_by(AISession.created_at.desc())