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/ui/src/index.ts

@@ -2,11 +2,14 @@ export { default as WAvatar } from './components/WAvatar.vue'
 export { default as WBadge } from './components/WBadge.vue'
 export { default as WBanner } from './components/WBanner.vue'
 export { default as WButton } from './components/WButton.vue'
+export { default as WComposer } from './components/WComposer.vue'
 export { default as WCheckbox } from './components/WCheckbox.vue'
 export { default as WDialog } from './components/WDialog.vue'
 export { default as WIcon } from './components/WIcon.vue'
 export { default as WIconButton } from './components/WIconButton.vue'
 export { default as WLogo } from './components/WLogo.vue'
+export { default as WMessageBubble } from './components/WMessageBubble.vue'
+export { default as WRoomItem } from './components/WRoomItem.vue'
 export { default as WSelect } from './components/WSelect.vue'
 export { default as WSpinner } from './components/WSpinner.vue'
 export { default as WSwitch } from './components/WSwitch.vue'
@@ -15,3 +18,4 @@ export { default as WTextField } from './components/WTextField.vue'
 
 export { iconNames, type IconName } from './icons'
 export { useTheme, type ThemeChoice } from './theme'
+export type { MessageStatus } from './chat'