Schedule backend: AniList client, AnimeFlow client, schedule matching

lib/src/schedule/ for the 1.0 Schedule tab (UI and docs come with the
schedule round):
- AniListClient: airingSchedules in a window, 50 per page, adult/music
  dropped; memory 10 min + disk 1 h cache, one Retry-After wait on 429,
  stale cache on failure; real User-Agent (AniList 403s some defaults).
- AnimeFlowClient: the full app API (me, schedule, series, follow,
  search, requests incl. approve/reject, users/scopes) with the user's
  Jellyfin token, only for a Jellyfin on AnimeFlow's parent domain;
  ETag/304, typed error codes, backoff on nginx's HTML 429, /me cached
  at most 60 s so scope changes show.
- matchSchedule + ScheduleRepository: AniList airings with AnimeFlow
  status by (episode anilist_id, episode), then absolute number, then
  air day; degrades to AniList-only when AnimeFlow fails.

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

apps/desktop/test/schedule_fake_server.dart

@@ -0,0 +1,51 @@
+import 'dart:convert';
+import 'dart:io';
+
+/// One request the fake server saw.
+class SeenRequest {
+  final String method;
+  final Uri uri;
+  final HttpHeaders headers;
+  final String body;
+  SeenRequest(this.method, this.uri, this.headers, this.body);
+}
+
+typedef FakeRoute = Future<void> Function(SeenRequest req, HttpResponse res);
+
+/// A localhost HTTP server for the Schedule clients: [handler] answers,
+/// [seen] records every request.
+class FakeServer {
+  FakeServer._(this._server) : url = 'http://${_server.address.host}:${_server.port}';
+  final HttpServer _server;
+  /// Kept after [close], so clients can try an address nobody answers.
+  final String url;
+  final seen = <SeenRequest>[];
+  late FakeRoute handler;
+
+  static Future<FakeServer> start(FakeRoute handler) async {
+    final s = FakeServer._(await HttpServer.bind(InternetAddress.loopbackIPv4, 0))..handler = handler;
+    s._server.listen((req) async {
+      final body = await utf8.decodeStream(req);
+      final r = SeenRequest(req.method, req.uri, req.headers, body);
+      s.seen.add(r);
+      try {
+        await s.handler(r, req.response);
+      } catch (e, st) {
+        // ignore: avoid_print
+        print('fake server handler failed: $e\n$st');
+        req.response.statusCode = 599;
+      }
+      await req.response.close();
+    });
+    return s;
+  }
+
+  Future<void> close() => _server.close(force: true);
+}
+
+void json(HttpResponse res, Object? body, {int status = 200, String? etag}) {
+  res.statusCode = status;
+  res.headers.contentType = ContentType.json;
+  if (etag != null) res.headers.set(HttpHeaders.etagHeader, etag);
+  res.write(jsonEncode(body));
+}