Add MSC4522 username colors, release notes dialog, and profile layout fixes.

Replace legacy profile style metadata with MSC4133 profile fields, add in-app update notes, tighten account profile name spacing, and wire desktop media save helpers through the client.

src/app/components/updates-dialog/index.ts

@@ -0,0 +1,3 @@
+export * from './UpdatesDialog';
+export * from './UpdatesDialogHost';
+export * from './UpdateMarkdownViewer';