fix(hubs): drop deleted items from recommended and home continue watching

The library Recommended tab never subscribed to deletion events, so
"Delete from server" left the episode sitting in Continue Watching
until a full reload. Make the tab DeletionAware (remove in place across
all hubs, then resync) and give DiscoverProvider the same subscription
so the home row and hubs drop deleted items too.

close #1486

test/providers/discover_provider_test.dart

@@ -14,18 +14,26 @@ import 'package:plezy/providers/multi_server_provider.dart';
 import 'package:plezy/services/data_aggregation_service.dart';
 import 'package:plezy/services/multi_server_manager.dart';
 import 'package:plezy/services/settings_service.dart';
+import 'package:plezy/utils/deletion_notifier.dart';
 import 'package:plezy/utils/watch_state_notifier.dart';
 
 import '../test_helpers/prefs.dart';
 
-MediaItem _item(String id, {String? parentId, String serverId = 'server_1'}) => MediaItem(
+MediaItem _item(
+  String id, {
+  String? parentId,
+  String? grandparentId,
+  MediaKind kind = MediaKind.episode,
+  String serverId = 'server_1',
+}) => MediaItem(
   id: id,
   backend: MediaBackend.plex,
-  kind: MediaKind.episode,
+  kind: kind,
   title: id,
   serverId: serverId,
   serverName: 'Server',
   parentId: parentId,
+  grandparentId: grandparentId,
 );
 
 MediaHub _hub(
@@ -223,6 +231,62 @@ void main() {
     expect(provider.onDeck.map((i) => i.id), ['ep-2']);
   });
 
+  test('deletion drops the item from on-deck and hubs, then refreshes continue watching only', () async {
+    aggregation.onDeckResult = () => [_item('ep-1'), _item('ep-2')];
+    aggregation.hubsResult = () => [
+      _hub('hub-1', items: [_item('ep-1'), _item('other')]),
+    ];
+    await provider.load();
+    final onDeckCallsBefore = aggregation.onDeckCalls;
+    final hubCallsBefore = aggregation.hubCalls;
+
+    var sawImmediateRemoval = false;
+    provider.addListener(() {
+      if (provider.onDeck.length == 1 && provider.onDeck.single.id == 'ep-2') {
+        sawImmediateRemoval = true;
+      }
+    });
+    aggregation.onDeckResult = () => [_item('ep-2')];
+
+    DeletionNotifier().notifyDeletedItem(item: _item('ep-1'));
+    await pumpEventQueue();
+
+    expect(sawImmediateRemoval, isTrue);
+    expect(provider.onDeck.map((i) => i.id), ['ep-2']);
+    expect(provider.hubs.single.items.map((i) => i.id), ['other']);
+    expect(aggregation.onDeckCalls, onDeckCallsBefore + 1);
+    expect(aggregation.hubCalls, hubCallsBefore);
+  });
+
+  test('deleting an ancestor removes its episodes from continue watching', () async {
+    aggregation.onDeckResult = () => [_item('ep-1', grandparentId: 'show-1'), _item('ep-2')];
+    await provider.load();
+    aggregation.onDeckResult = () => [_item('ep-2')];
+
+    DeletionNotifier().notifyDeletedItem(item: _item('show-1', kind: MediaKind.show));
+    await pumpEventQueue();
+
+    expect(provider.onDeck.map((i) => i.id), ['ep-2']);
+  });
+
+  test('download-only deletion leaves lists untouched and triggers no refetch', () async {
+    aggregation.onDeckResult = () => [_item('ep-1')];
+    aggregation.hubsResult = () => [
+      _hub('hub-1', items: [_item('ep-1')]),
+    ];
+    await provider.load();
+    final onDeckCallsBefore = aggregation.onDeckCalls;
+    final hubCallsBefore = aggregation.hubCalls;
+
+    DeletionNotifier().notifyDeletedItem(item: _item('ep-1'), isDownloadOnly: true);
+    await pumpEventQueue();
+
+    expect(provider.onDeck.map((i) => i.id), ['ep-1']);
+    expect(provider.hubs.single.items.map((i) => i.id), ['ep-1']);
+    expect(aggregation.onDeckCalls, onDeckCallsBefore);
+    expect(aggregation.hubCalls, hubCallsBefore);
+  });
+
   test('library order change re-sorts hubs without any refetch', () async {
     aggregation.hubsResult = () => [_hub('hub-lib2', libraryId: 'lib-2'), _hub('hub-lib1', libraryId: 'lib-1')];
     await provider.load();