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/sidebar.py

@@ -147,13 +147,20 @@ async def get_sidebar_stats(
         for row in recent_result.all()
     ]
 
-    # --- Escalation count (team-wide pending escalations) ---
+    # --- Escalation count (team/account-wide pending escalations) ---
     escalation_count = 0
     if current_user.team_id:
+        esc_scope = AISession.team_id == current_user.team_id
+    elif current_user.account_id:
+        esc_scope = AISession.account_id == current_user.account_id
+    else:
+        esc_scope = None
+
+    if esc_scope is not None:
         esc_result = await db.execute(
             select(func.count()).where(
                 and_(
-                    AISession.team_id == current_user.team_id,
+                    esc_scope,
                     AISession.status == "requesting_escalation",
                 )
             )