Web client (warp-web) with E2EE, and two sync fixes

apps/web: a Matrix client for the browser on Vue 3, Tailwind and
matrix-js-sdk, built on @warp/ui. Like the admin panel it is an optional,
separate service: warp-web embeds the built app, serves /config.json and
proxies only /_matrix/client and /_matrix/media to the homeserver (or,
with -public-homeserver, lets the browser call it directly).
Sign-in and sign-up with registration tokens, room list, timeline with
back-pagination, text, images, video and files over authenticated media,
local echo with sent/read/failed states, receipts, typing, invites,
creating, joining and leaving rooms, room info, settings, phone layout.
End-to-end encryption through the Rust crypto: encrypted messages and
files, emoji verification, key backup setup and restore.

apps/ui: WRoomItem, WMessageBubble and WComposer from the brand package,
and the icons the client needs.

syncapi fixes found with the client:
- A room joined inside the sync window was sent as the join alone with
  limited: false, so clients thought they had the whole room. It is now
  read like an initial sync; a profile change is not mistaken for a join.
- A live typing notification was reported on every sync, so every long
  poll returned at once while anybody typed. Typing now has a position
  in the sync token and is reported when it changes, including the empty
  list when the last person stops.

Also: Dockerfile, a `web` compose profile, Makefile targets, a CI job
with a proxy smoke test, docs. PLAN.md moves out of the repository.

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

apps/web/src/components/RoomRow.vue

@@ -0,0 +1,34 @@
+<script setup lang="ts">
+import { WRoomItem } from '@warp/ui'
+import { useMedia } from '@/matrix/media'
+
+// WRoomItem with the room's avatar loaded from the media repository.
+
+const props = defineProps<{
+  name: string
+  avatarMxc?: string
+  preview?: string
+  time?: string
+  unread?: number
+  mention?: boolean
+  encrypted?: boolean
+  active?: boolean
+  presence?: 'online' | 'away' | 'busy' | 'offline'
+}>()
+
+const { url } = useMedia(() => props.avatarMxc, { width: 80, height: 80 })
+</script>
+
+<template>
+  <WRoomItem
+    :name="name"
+    :avatar="url"
+    :preview="preview"
+    :time="time"
+    :unread="unread"
+    :mention="mention"
+    :encrypted="encrypted"
+    :active="active"
+    :presence="presence"
+  />
+</template>