Keeps develop's per-user Slack delivery, escalation and mute work; the in_app_min_severity changeset moves to qbit-alerts:29; the Notifications preferences section gains Slack per category; pause also skips non-security Slack; the summary schema carries preferencesSection (alerts extension 1.1.0). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>