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/schemas/sidebar.py

@@ -40,6 +40,7 @@ class SidebarStatsResponse(BaseModel):
     resolved_today: int
     active_count: int
     total_session_minutes_today: int
+    escalation_count: int = 0
     tree_counts: SidebarTreeCounts
     active_sessions: list[SidebarActiveSession]
     recent_completions: list[SidebarRecentSession]