banners table (title/body/level/active/dismissible/schedule window).
GET /banners/active for signed-in users; admin CRUD under /admin/banners.
BannerBar renders above the header with per-banner dismissal
(localStorage); admin console gains an Announcements section;
`containr banners` manages them and `auth status` prints active ones.
Generated with [Devin](https://devin.ai)
Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
