- Replace every Mantine component with the toolkit (Button, Callout, IconButton) or plain markup; remove MantineProvider, its stylesheet and the --mantine variable bridge; keep its form-font reset in reader.css. Uninstall @mantine/core and @mantine/hooks.
- ActionMenu/ActionSheet (ui/action-menu.tsx): the file manager's Mantine Menu, the shelf pick dialog and the media <details> menus (catalog, narrators, detail, libraries, library rows, folders, chapters, queue, resource panel, favorites filter) are one compact Sheet menu.
- Toolkit Callout for page-level messages; operation failures go to FloatingNotice; .page-state for whole-page loading/error.
- Shared SourcesHeader and SourceBookDetailSheet; source editor and credentials pages rebuilt without Mantine, deleting a source now asks first.
- Remove dead code: SettingsPage (unrouted), MiniPlayer, ui/dom.ts (formatters moved to lib/format.ts), the unused metadata form dialog, useAppThemeDark.
- ui:review react-app passes again: fixed stale steps (/settings, mini player, login race, missing-edition detail).