feat(app): card tiles: the front, the tags, the options

A studyset's cards list as bordered rows of one height showing the
front, the card's tags above it and a badge when devices changed it
differently; tapping opens the composer, "…" offers editing and
deleting (after asking).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_localizations_en.dart

@@ -761,6 +761,21 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get matchingMinItems => 'At least two items required';
 
+  @override
+  String get cardTileOptions => 'Options';
+
+  @override
+  String get cardTileEdit => 'Edit';
+
+  @override
+  String get cardTileDelete => 'Delete';
+
+  @override
+  String get cardTileUntitled => 'Untitled';
+
+  @override
+  String get cardTileConflict => 'Changed on two devices';
+
   @override
   String get commonCancel => 'Cancel';