The root catch-all page ([...slug].vue) redirected every unknown URL to
/admin, and the worker fell back to the SPA for any path — so no matter
what page was opened, the URL ended up at baseurl/admin.
- Extract the console into ConsolePage.vue; the active tab now mirrors
the URL path: /admin (groups), /admin/groups, /admin/logs, /admin/audit
(tab switches use router.replace; unknown slugs render 404)
- admin.vue and admin/[slug].vue become thin wrappers
- Delete the root [...slug].vue catch-all redirect
- server.ts: notFound serves ASSETS (SPA + _nuxt chunks) only for
/admin-prefixed paths; every other unknown URL returns a JSON 404
