The old panel kept its active tab in a store, so every page sat at
/admin, the sidebar duplicated the webmail rail by hand, and each page
was a stack of boxed cards with their own save buttons. Plugin settings
were only reachable through a gear icon in a row of five.
- one catch-all route for the whole panel; pages switch through
history.pushState, so `/admin/plugins/<id>`, the back button, bookmarks
and connector links all work without a route transition
- sidebar laid out like the user settings: back to mail, search over
pages and their sections, two group headings, change password and
sign out at the bottom; the phone shows a list, then the page
- pages use SettingsSection rows instead of nested cards, with one page
header, one flash message and one save bar at the bottom (Discard,
Save, Ctrl+S); the unsaved-changes prompt still guards leaving
- plugins and themes are lists of rows with a toggle each; a row opens
the extension's own page with its settings, force-on, permissions,
kept versions and removal
- overview shows stat tiles, server facts and recent activity
- old `/admin?tab=x` links redirect; the tab store is gone and the
connector registry resolves admin links to the page URL
- `NEXT_TURBOPACK_ROOT` overrides the Turbopack root so `next dev` runs
from a worktree with a junctioned node_modules