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>

apps/mobile/src/components/NowPlayingCard.tsx

@@ -5,7 +5,6 @@ import { useEffect, useRef, useState } from 'react';
 import { Linking, Pressable, StyleSheet, Text, View } from 'react-native';
 import Animated, {
   FadeIn,
-  FadeInDown,
   FadeOut,
   useAnimatedStyle,
   useSharedValue,
@@ -98,7 +97,7 @@ export function NowPlayingCard({
         </View>
       </View>
 
-      <Animated.View key={np.track.id} entering={FadeInDown.duration(380).springify()} exiting={FadeOut.duration(200)}>
+      <Animated.View key={np.track.id} entering={FadeIn.duration(250)} exiting={FadeOut.duration(200)}>
         <TrackRow track={np.track} preferred={preferred} expanded={expanded} onToggle={toggle} />
       </Animated.View>
       <ProgressBar np={np} compact={!expanded} />

apps/mobile/src/components/UpdateBanner.tsx

@@ -0,0 +1,32 @@
+import { StyleSheet } from 'react-native';
+import { installUpdate, updaterAvailable, useUpdateState } from '@/lib/updates';
+import { Body, Button, Card, Heading } from './ui';
+
+/** "Update ready" on the feed, once a newer version has downloaded (lib/updates.ts). */
+export function UpdateBanner() {
+  const state = useUpdateState();
+  if (!updaterAvailable || (state.status !== 'ready' && state.status !== 'installing')) return null;
+  return (
+    <Card highlighted>
+      <Heading>musicshare {state.update.version} is ready</Heading>
+      {state.update.notes ? (
+        <Body muted style={styles.notes} numberOfLines={4}>
+          {state.update.notes}
+        </Body>
+      ) : null}
+      <Button
+        small
+        variant="primary"
+        title={state.status === 'installing' ? 'Installing…' : 'Install update'}
+        disabled={state.status === 'installing'}
+        onPress={() => installUpdate(true)}
+        style={styles.button}
+      />
+    </Card>
+  );
+}
+
+const styles = StyleSheet.create({
+  notes: { fontSize: 13 },
+  button: { alignSelf: 'flex-start' },
+});