- Convert discover, stats, status, and system-health server actions to
proper API route handlers under `app/api/`; delete `lib/actions/explore.ts`,
`lib/actions/settings.ts`, and `lib/actions/setup.ts`
- Add `use-discover`, `use-stats`, and `use-system-health` SWR hooks
that call the new routes; update `command-palette`, `title-card`,
`update-toast`, and `stats-display` to consume them
- Lift auth centering wrapper from individual login/register pages into
`(auth)/layout.tsx`; switch both pages from `auth.api.getSession` to
the cached `getSession()` helper
- Relocate setup wizard from `app/(auth)/setup/` to `app/setup/` (outside
auth group) with dedicated `copy-button` and `refresh-button` client
components
- Move `not-found.tsx` and `error.tsx` to app root so they apply
globally instead of only within the pages route group
