Player: now-playing title with cover, start banner, one status pill; media art for everyone

The swapper sends the media's poster and banner once (`art`, Jellyfin
images or AniList by parsed name); state carries their hashes and every
member fetches them from /i/ like avatars. state.media.swapBy names who
put the media up. uosc and the standard bar show cover, title and
episode; a banner card shows before playback starts. The top-left health
pill and the waiting pill become one frosted status pill in plain words.

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

apps/desktop/lib/src/session/media_art.dart

@@ -0,0 +1,95 @@
+import 'dart:async';
+import 'dart:io';
+import 'dart:typed_data';
+
+import 'package:flutter/foundation.dart';
+import 'package:sync_relay_core/core.dart';
+
+import '../files/name_parser.dart';
+import '../schedule/anilist.dart';
+
+// Art for media this client swapped in (`art`, see PROTOCOL.md "Media
+// art"): Jellyfin images with this install's account, else an AniList
+// title search. Everything here fails quietly to "no art".
+
+/// Poster and banner bytes; either may be null.
+typedef ArtBytes = ({Uint8List? poster, Uint8List? banner});
+
+/// Series poster (the item's own for movies) and series/item backdrop,
+/// else its Banner image, scaled by Jellyfin to fit the caps.
+Future<ArtBytes> jellyfinArt(JellyfinClient client, String itemId,
+    {Future<Uint8List?> Function(Uri url, Map<String, String> headers, int maxBytes) fetch = fetchImage}) async {
+  final item = await client.item(itemId).timeout(const Duration(seconds: 10));
+  final seriesPoster = item.seriesId != null && item.seriesPrimaryImageTag != null
+      ? JellyfinImageRef(item.seriesId!, JellyfinImageType.primary, item.seriesPrimaryImageTag!)
+      : null;
+  final poster = seriesPoster ?? item.image(JellyfinImageType.primary);
+  var banner = item.image(JellyfinImageType.backdrop);
+  if (banner == null) {
+    var owner = item;
+    if (item.seriesId != null && item.ownImage(JellyfinImageType.banner) == null) {
+      try {
+        owner = await client.item(item.seriesId!).timeout(const Duration(seconds: 10));
+      } catch (_) {}
+    }
+    banner = owner.ownImage(JellyfinImageType.banner);
+  }
+  final headers = client.authHeaders;
+  final (p, b) = await (
+    poster == null
+        ? Future<Uint8List?>.value()
+        : fetch(client.imageUrl(poster, maxHeight: 450, quality: 85), headers, RelayConstants.maxPosterBytes),
+    banner == null
+        ? Future<Uint8List?>.value()
+        : fetch(client.imageUrl(banner, maxWidth: 1280, quality: 85), headers, RelayConstants.maxBannerBytes),
+  ).wait;
+  return (poster: p, banner: b);
+}
+
+/// The series of release name [name] on AniList: cover and banner; null
+/// when the name says nothing or AniList knows no match.
+Future<ArtBytes?> aniListArt(AniListClient aniList, String name,
+    {Future<Uint8List?> Function(Uri url, Map<String, String> headers, int maxBytes) fetch = fetchImage}) async {
+  final series = parseReleaseName(name).series.trim();
+  if (series.isEmpty) return null;
+  final match = await aniList.searchMedia(series);
+  if (match == null) return null;
+  Future<Uint8List?> get(String? url, int maxBytes) async {
+    final uri = url == null ? null : Uri.tryParse(url);
+    return uri == null ? null : fetch(uri, const {}, maxBytes);
+  }
+
+  final (cover, banner) = await (
+    get(match.cover, RelayConstants.maxPosterBytes),
+    get(match.banner, RelayConstants.maxBannerBytes),
+  ).wait;
+  final poster = cover ?? (match.coverSmall == match.cover ? null : await get(match.coverSmall, RelayConstants.maxPosterBytes));
+  return (poster: poster, banner: banner);
+}
+
+/// GET [url]: the bytes when 200, at most [maxBytes] and a known image
+/// type (see `avatarImageType`); else null.
+Future<Uint8List?> fetchImage(Uri url, Map<String, String> headers, int maxBytes) async {
+  final client = HttpClient()..connectionTimeout = const Duration(seconds: 10);
+  try {
+    final req = await client.getUrl(url);
+    headers.forEach(req.headers.set);
+    final resp = await req.close().timeout(const Duration(seconds: 15));
+    if (resp.statusCode != 200 || resp.contentLength > maxBytes) {
+      await resp.drain<void>().catchError((_) {});
+      return null;
+    }
+    final builder = BytesBuilder(copy: false);
+    await for (final chunk in resp.timeout(const Duration(seconds: 15))) {
+      builder.add(chunk);
+      if (builder.length > maxBytes) return null;
+    }
+    final bytes = builder.takeBytes();
+    return avatarImageType(bytes) == null ? null : bytes;
+  } catch (e) {
+    debugPrint('art: fetch failed: $e');
+    return null;
+  } finally {
+    client.close(force: true);
+  }
+}