Notification settings (admin)

Settings → Notifications (/settings/notifications).

Three columns of toggles (as implemented on the page):

1. In-app — bell / notifications list
2. Email — SMTP; some types cannot be emailed (can_be_emailed false)
3. Slack — webhook; some types cannot post to Slack

Each section has a master toggle. Per-row switches update immediately (PATCH on that setting).

This is system policy, not a per-user preference screen. Combine with Global email notifications and a valid webhook.

User-facing behavior: Notifications & watchers.