Add a super-admin-only Groups tab to create, edit and delete groups
(name, admin ids, owner scope). Routes now require a group via a select
in the editor, group names are shown on route cards, and the new
useMe/useGroups composables back the UI.
Add a prefers-color-scheme dark palette to the Nuxt console so it
follows the device/OS theme automatically. Tokenize the previously
hardcoded dot-grid, sticky header, switch knob and overlay scrim so
they invert correctly, and set color-scheme: dark for native controls.
Add an admin WebUI (Nuxt static SPA in admin/, served via the ASSETS
binding) for managing routes and viewing send logs. Access is gated by
GitHub OAuth plus an ADMIN_USER_IDS whitelist with cookie sessions
(admin-session.ts). Expose routes/logs CRUD API (admin-routes.ts), add a
discord-link mapping in token-store.ts, and mount admin routes with an
SPA assets fallback in the server.
