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_de.dart

@@ -1271,6 +1271,55 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get cardSenses => 'Wortbedeutungen';
 
+  @override
+  String get cardReportTitle => 'Fehler melden';
+
+  @override
+  String get cardReportSubtitle =>
+      'Markiere diese Karte, um sie später zu finden und zu korrigieren.';
+
+  @override
+  String get cardReportTypo => 'Tippfehler';
+
+  @override
+  String get cardReportGrammar => 'Grammatik';
+
+  @override
+  String get cardReportContent => 'Inhalt';
+
+  @override
+  String get cardReportOther => 'Sonstiges';
+
+  @override
+  String get cardReportNote => 'Notiz';
+
+  @override
+  String get cardReportNoteHint => 'Was muss korrigiert werden?';
+
+  @override
+  String get cardReportSubmit => 'Melden';
+
+  @override
+  String get cardReported => 'Zur Korrektur markiert';
+
+  @override
+  String get cardResolveReport => 'Meldung erledigen';
+
+  @override
+  String get cardReportResolved => 'Meldung erledigt';
+
+  @override
+  String get cardBuriedBadge => 'Zurückgestellt';
+
+  @override
+  String get cardUnbury => 'Zurückstellung aufheben';
+
+  @override
+  String get cardTileBuried => 'Karteikarte bis morgen zurückgestellt';
+
+  @override
+  String get cardTileUnburied => 'Karteikarte nicht mehr zurückgestellt';
+
   @override
   String get cardFilterTooltip => 'Filter';