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/ToastList.vue

@@ -0,0 +1,33 @@
+<script setup lang="ts">
+import { WIcon, WIconButton } from '@warp/ui'
+import { useToasts } from '@/stores/toasts'
+
+const toasts = useToasts()
+const icon = { success: 'shield-check', danger: 'shield-alert', info: 'server' } as const
+const tone = {
+  success: 'bg-teal-soft text-teal-text',
+  danger: 'bg-danger-soft text-danger',
+  info: 'bg-info-soft text-info',
+} as const
+</script>
+
+<template>
+  <div
+    class="pointer-events-none fixed inset-x-4 bottom-4 z-40 flex flex-col items-end gap-2 sm:left-auto sm:w-96"
+    aria-live="polite"
+  >
+    <div
+      v-for="t in toasts.items"
+      :key="t.id"
+      :class="[
+        'pointer-events-auto flex w-full items-center gap-3 rounded-md border border-line py-2 pr-1 pl-4 shadow-float',
+        tone[t.tone],
+      ]"
+      :role="t.tone === 'danger' ? 'alert' : 'status'"
+    >
+      <WIcon :name="icon[t.tone]" />
+      <p class="flex-1 text-ink">{{ t.text }}</p>
+      <WIconButton icon="close" label="Dismiss" @click="toasts.dismiss(t.id)" />
+    </div>
+  </div>
+</template>