Admin panel (warp-admin) and the apps/ui design system

apps/ui: Warp's design system for Vue 3 + Tailwind v4. Tokens, fonts,
icons and logo come from the brand package, with a Tailwind theme on the
tokens and Vue components on the brand component styles.

apps/admin: the admin panel as a separate, optional service. warp-admin
embeds the built Vue app and proxies only the login endpoints and
/_warp/admin/v1 to the homeserver. Pages: dashboard, users, rooms,
federation, registration and tokens, server notices, application
services, audit log.

Also: pnpm workspace, go.work entry, Dockerfile, an `admin` compose
profile, Makefile targets, a CI job with a proxy smoke test, and docs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/admin-api.md

@@ -2,7 +2,8 @@
 
 Everything under `/_warp/admin/v1` is Warp's own, not Matrix. Clients use
 the Client-Server API; this is the operator's surface and the backend for
-the admin panel (`apps/admin`, PLAN.md section 8.1).
+the admin panel ([`apps/admin`](../apps/admin/README.md), a separate,
+optional `warp-admin` service).
 
 ## Authentication