Player overlay as one piece, Up next always warm and on every source, Jellyfin never unmarks a watched episode

- Overlay: one layout for both designs (top bar with Up next as one of
  its buttons; one action band above the controls for the status pill,
  skips, next episode and end cards), one glass recipe (AppGlass) and
  one pill (FloatingPill); hovering any of them, or the open queue,
  holds the controls up.
- Up next: the first item (or the first continuation episode) is kept
  resolved on the app that puts it up, refreshed before it expires;
  Schedule and drop/paste can queue too.
- Jellyfin: WatchSession (core) counts real watched coverage; an
  episode is watched at 80 % or at its ending after half; a played one
  is re-marked after Playing (10.11 unmarks on open) and never gets a
  position; a peek leaves the old resume point; part-way resume points
  stay under 85 %.

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

apps/desktop/test/jellyfin_e2e_test.dart

@@ -149,6 +149,9 @@ class _FakeJellyfin {
       res.statusCode = 204;
       return res.close();
     }
+    if (path.startsWith('/UserPlayedItems/') || path.startsWith('/UserItems/')) {
+      return json({'Played': path.startsWith('/UserPlayedItems/'), 'PlaybackPositionTicks': 0});
+    }
     if (RegExp(r'^/Videos/\w+/stream$').hasMatch(path)) return _stream(req);
     res.statusCode = 404;
     await res.close();
@@ -378,8 +381,13 @@ void main() {
         expect(ep1.last, 'Stopped');
         expect(ep1.where((k) => k == 'Stopped'), hasLength(1));
         final stopped1 = aCalls.lastWhere((s) => s.body?['ItemId'] == _ep1);
-        expect(stopped1.body!['PositionTicks'], greaterThan(19 * jellyfinTicksPerSecond),
-            reason: 'played to the end');
+        // Part of it watched, then a seek to the end: not watched (see
+        // WatchSession). A resume point capped at 85 % of the 20 s, so
+        // Jellyfin cannot mark it played on its own.
+        expect(stopped1.body!['PositionTicks'], lessThan(18 * 10000000),
+            reason: 'part way: resume point under 90 %, so not marked played');
+        expect(jelly.calls.any((c) => c.method == 'POST' && c.path == '/UserPlayedItems/$_ep1'), isFalse,
+            reason: 'seeking to the end is not watching');
         expect(stopped1.body!['PlaySessionId'], 'ps-ua-$_ep1');
         expect(ep2.first, 'Playing');
         expect(ep2.last, 'Stopped', reason: 'leaving reports Stopped');