Add the browser version, a toolbar, description previews and hints

Browser version
- Self-hosted proxy (server/) that serves the web build and bridges WebSocket
  connections to Mumble servers over TLS, with a server allowlist or allow-any mode
- WebSocket transport and a browser platform layer; identities live in the browser
- npm run build:web, dev:web, proxy and test:e2e:web; proxy unit tests

Interface
- Toolbar next to mute and deafen: description editor, settings, expand or collapse all
- Channels with a description show a marker; resting on the row previews it
- Collapse all keeps channels with people open
- Hints (title tooltips) can be switched on in a new Accessibility settings tab
- New identities can set the username suggested when connecting
- Own user information tells the client address from the one the server sees

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

.gitignore

@@ -1,6 +1,7 @@
 node_modules/
 dist/
 dist-web/
+dist-proxy/
 dist-electron/
 release/
 *.log