Admin Inject Test Event

Synthesize a fake entry / exit / lifecycle notification for a bot.

Drives the same notifications.fanout_event helper the reconciler uses on real ticks, so every follower of the bot whose channel preferences include the enabled channel gets a row in tw_notifications_log:

• in_app — status='sent' (visible in the bell immediately)
• email — status='queued' (delivery worker picks it up ≤60s)
• webhook — status='queued' (delivery worker not yet wired)

Body: bot_id (required): the bot to attribute the fake event to. event_type: 'entry' | 'exit' | 'both'. Default 'exit'. payload: optional dict of overrides merged over the synthesized default payload for the event type.