The three public webhook emitters in chat_helpers and webhook_routes
schedule deliveries via asyncio.create_task(webhook_manager.fire(...)),
which bypasses WebhookManager._bg_tasks. asyncio only holds a weak
reference to the outer task, so the GC can collect it mid-delivery and
the webhook is silently dropped.
Route all three through webhook_manager.fire_and_forget() so the task
is tracked by _spawn_tracked() and the manager owns the full lifecycle.
Adds an AST-level guard test that scans routes/ for direct
asyncio.create_task wrapping webhook_manager.fire(...) to prevent
regressions.
Wei Hong