feat(app): a character card for kanji and kana

One card type for both (card schema 7): the character on the front, its
meanings and a kanji's on and kun readings, each merging on its own. A
kana's romaji is its meaning, so kana are studied, and later written,
exactly as kanji are. The composer offers it beside the other kinds, each
kind of reading on one line (ショク、ジキ); studying shows the character
large and, with the answer, its meanings and readings (the other way round
when asked from the back); the card browser filters by it and finds a kun
reading without its okurigana dot; the Markdown export writes its meanings
and readings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_localizations_en.dart

@@ -2016,6 +2016,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get composerKindMap => 'Map';
 
+  @override
+  String get composerKindCharacter => 'Character';
+
   @override
   String get composerLabelFront => 'Front';
 
@@ -2028,6 +2031,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get composerLabelPrompt => 'Prompt';
 
+  @override
+  String get composerLabelCharacter => 'Character';
+
   @override
   String get composerLabelBack => 'Back';
 
@@ -2046,6 +2052,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get composerPlaceholderPrompt => 'Add prompt';
 
+  @override
+  String get composerPlaceholderCharacter => 'Add a kanji or kana';
+
   @override
   String get composerAddAnswer => 'Add answer';
 
@@ -2208,6 +2217,29 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get vocabularyRemoveSense => 'Remove sense';
 
+  @override
+  String get characterPrimaryMeaningHint =>
+      'Primary meaning, or a kana\'s romaji';
+
+  @override
+  String get characterOnReadings => 'On readings';
+
+  @override
+  String get characterOnReadingsHint => 'From Chinese, in katakana: ショク、ジキ';
+
+  @override
+  String get characterKunReadings => 'Kun readings';
+
+  @override
+  String get characterKunReadingsHint =>
+      'Japanese, in hiragana, okurigana after a dot: た.べる';
+
+  @override
+  String get characterOn => 'On';
+
+  @override
+  String get characterKun => 'Kun';
+
   @override
   String get matchingCategories => 'Categories';
 
@@ -4397,6 +4429,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get cardBrowserTypeMap => 'Maps only';
 
+  @override
+  String get cardBrowserTypeCharacter => 'Characters only';
+
   @override
   String get cardBrowserFilterTag => 'Tag';