The Android app updates itself from our Gitea releases; feed cards fade in instead of bouncing

- API: GET /app/android/latest reads the latest Gitea release (ANDROID_RELEASES_URL, optional token for a
  private repo) with the APK's SHA-256 from SHA256SUMS; GET /app/android/apk/:name streams that APK.
- App (modules/updater): downloads in the background, checks the SHA-256, and installs through
  PackageInstaller: quietly once when leaving the app (Android 12+), otherwise from the feed banner or
  Settings > App version. F-Droid builds leave it out and drop the install permissions.
- CI: the release notes come from the fastlane changelog; the app shows the part above ---.
- Settings: Create-account and Link Spotify buttons for Last.fm and ListenBrainz.

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

packages/shared/src/updates.ts

@@ -0,0 +1,31 @@
+/** The newest Android release, as the server reports it (GET /app/android/latest). */
+export interface AppUpdateDTO {
+  /** e.g. "1.2.0" (the release tag without its "v"). */
+  version: string;
+  /** Where to download the APK (through our server, so the release host can stay private). */
+  apkUrl: string;
+  /** Hex SHA-256 of the APK; the phone checks it before installing. */
+  sha256: string;
+  size: number;
+  /** What's new, from the release notes. */
+  notes: string | null;
+  publishedAt: string;
+}
+
+/** "1.10.0" → [1, 10, 0]; null for anything that isn't a plain dotted version (an optional leading "v" is fine). */
+export function parseVersion(version: string): number[] | null {
+  const m = /^v?(\d+(?:\.\d+)*)$/.exec(version.trim());
+  return m ? m[1]!.split('.').map(Number) : null;
+}
+
+/** True when `candidate` is a later version than `current`. Unparseable versions are never newer. */
+export function isNewerVersion(candidate: string, current: string): boolean {
+  const a = parseVersion(candidate);
+  const b = parseVersion(current);
+  if (!a || !b) return false;
+  for (let i = 0; i < Math.max(a.length, b.length); i++) {
+    const diff = (a[i] ?? 0) - (b[i] ?? 0);
+    if (diff !== 0) return diff > 0;
+  }
+  return false;
+}