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/utils/appVersion.ts

@@ -0,0 +1,10 @@
+import { getVersion } from '@tauri-apps/api/app';
+
+/** Returns the running app version (Electron shim or Tauri). */
+export async function getAppVersion(): Promise<string> {
+  try {
+    return await getVersion();
+  } catch {
+    return 'unknown';
+  }
+}