feat(app): report what is wrong with a card, and bury cards from the list

- "Report an error", from a card's menu while studying or in the list:
  a category (typo, grammar, content, other) and a note. The card is
  marked to be fixed, and still studied; the list shows the category
  (the note on hover), and "Resolve report" takes it back. A report is
  a revision of the card, so it follows it to every device.
- The list buries a card until tomorrow and brings it back ("Unbury"),
  showing "Buried" meanwhile.
- Each of these says so with an Undo.

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

@@ -1262,6 +1262,55 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get cardSenses => 'Senses';
 
+  @override
+  String get cardReportTitle => 'Report an error';
+
+  @override
+  String get cardReportSubtitle =>
+      'Flag this card so you can find and fix it later.';
+
+  @override
+  String get cardReportTypo => 'Typo';
+
+  @override
+  String get cardReportGrammar => 'Grammar';
+
+  @override
+  String get cardReportContent => 'Content';
+
+  @override
+  String get cardReportOther => 'Other';
+
+  @override
+  String get cardReportNote => 'Note';
+
+  @override
+  String get cardReportNoteHint => 'What needs fixing?';
+
+  @override
+  String get cardReportSubmit => 'Report';
+
+  @override
+  String get cardReported => 'Flagged for fixing';
+
+  @override
+  String get cardResolveReport => 'Resolve report';
+
+  @override
+  String get cardReportResolved => 'Report resolved';
+
+  @override
+  String get cardBuriedBadge => 'Buried';
+
+  @override
+  String get cardUnbury => 'Unbury';
+
+  @override
+  String get cardTileBuried => 'Flashcard buried until tomorrow';
+
+  @override
+  String get cardTileUnburied => 'Flashcard unburied';
+
   @override
   String get cardFilterTooltip => 'Filter';