feat(dictionary): characters of Chinese, Korean and Greek, written by hand; pinyin typed

Parity with Japanese's kanji and kana:

- The characters' tab is named by its language (Hanzi, Hangul & Hanja,
  Alphabet), its groups too: HSK levels and the characters in common use
  (Hong Kong's grades for traditional ones); Hangul and the Hanja taught
  in schools; Greek's letters. Radicals for Chinese and Korean in their
  own forms (讠 for 言 in simplified Chinese), none for Greek.
- A character's readings are named as its language names them: On and
  Kun, Pinyin, Eum and Hun (음, 훈); a letter means its sound and name.
- How characters are written comes by language: Chinese from Make Me a
  Hanzi (its medians in KanjiVG's square, Arphic Public License, a data
  file beside the app, never in cards), the Hangul letters drawn by the
  curator; a Korean word is written letter by letter (닭: ㄷ ㅏ ㄺ). Words
  of alphabets (German, Greek) aren't written by hand.
- A Chinese word's pinyin is typed in a session, tone numbers turning
  into marks (ni3 → nǐ); KRDict's levels (초급, 중급, 고급) tag Korean
  words; a Korean word's pronunciation shows in brackets ([가치]).
- Smaller: Look up in the composer keeps a noun's article; the Watch
  filter names its level list; hints and placeholders by language.

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/test/feature/kanji/model/radical_test.dart

@@ -34,4 +34,21 @@ void main() {
   test("a radical's label is the dictionary's", () {
     expect(radicalLabel(85), 'radical:85');
   });
+
+  test('the forms a radical takes in each language: simplified Chinese its '
+      "own, traditional Chinese and Korean without Japanese's own", () {
+    final speech = radicals[148];
+    final dragon = radicals[211];
+    final food = radicals[183];
+    expect(radicalFormsIn(speech, 'zh-Hans'), ['讠']);
+    expect(radicalFormsIn(speech, 'zh-Hant'), isEmpty);
+    expect(radicalFormsIn(dragon, 'ja'), ['竜']);
+    expect(radicalFormsIn(dragon, 'zh'), ['龙']);
+    expect(radicalFormsIn(dragon, 'ko'), isEmpty);
+    // Simplified Chinese writes 食 as 饣 at a character's side, not 飠.
+    expect(radicalFormsIn(food, 'zh-CN'), ['饣']);
+    expect(radicalFormsIn(food, 'zh-TW'), ['飠']);
+    expect(radicalsIn('zh-Hans')[148].variants, ['讠']);
+    expect((hasRadicals('ko'), hasRadicals('el')), (true, false));
+  });
 }