chore: Halkyon Learn moves into apps/learn

Its server, client, app and curator, and the tools that write its
assets (maps, Anki fixtures, icons), as they are; paths are fixed in
the commits that follow.

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

apps/learn/halkyon_learn_curator/test/krdict_test.dart

@@ -0,0 +1,144 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:archive/archive.dart';
+import 'package:halkyon_learn_curator/src/sources/krdict.dart';
+import 'package:halkyon_learn_curator/src/sources/wiktionary.dart';
+import 'package:halkyon_learn_curator/src/wordfreq.dart';
+import 'package:test/test.dart';
+
+void main() {
+  /// The fixture packed as KRDict packs its export: its first file.
+  List<int> export() => ZipEncoder().encodeBytes(
+    Archive()..add(
+      ArchiveFile.bytes(
+        '1_5000_20260919.json',
+        File('test/fixtures/krdict-sample.json').readAsBytesSync(),
+      ),
+    ),
+  );
+
+  Future<List<Map<String, Object?>>> converted({
+    WordFrequencies? frequencies,
+    WiktionaryKorean? korean,
+  }) async {
+    final (:version, :entries) = krdictExport(export());
+    return [
+      for (final line in await krdictDictionary(
+        entries,
+        sourceVersion: version,
+        frequencies: frequencies,
+        korean: korean,
+      ).toList())
+        jsonDecode(line) as Map<String, Object?>,
+    ];
+  }
+
+  test('an export of another shape is refused rather than written as a '
+      'dictionary of no words', () async {
+    for (final files in [
+      <ArchiveFile>[],
+      [ArchiveFile.bytes('1_5000_20260919.xml', utf8.encode('<xml/>'))],
+      [
+        ArchiveFile.bytes(
+          '1_5000_20260919.json',
+          utf8.encode(jsonEncode({'LexicalResource': <String, Object?>{}})),
+        ),
+      ],
+    ]) {
+      final archive = Archive();
+      files.forEach(archive.add);
+      final zip = ZipEncoder().encodeBytes(archive);
+      final (version: _, :entries) = krdictExport(zip);
+
+      await expectLater(entries.toList(), throwsFormatException);
+    }
+  });
+
+  test("KRDict's words with their level, pronunciation where it differs from "
+      'the spelling, Hanja, forms and English senses', () async {
+    final [header, ...entries] = await converted();
+
+    expect(header['source'], 'krdict');
+    expect(header['language'], 'ko');
+    expect(header['sourceVersion'], '2026-09-19');
+    expect(
+      [
+        for (final credit in header['credits']! as List)
+          (credit as Map)['name'],
+      ],
+      ['한국어기초사전 (Basic Korean Dictionary)'],
+    );
+    final school = entries.singleWhere((entry) => entry['headword'] == '학교');
+    expect(school['id'], '73276');
+    expect(school['reading'], '학꾜');
+    expect(school['labels'], ['level:beginner']);
+    expect(school['keys'], containsAll(['학교', '學校', 'school']));
+    const definition =
+        'An institution that educates students according to a specific '
+        'purpose, curriculum, system, etc.';
+    expect(school['entry'], {
+      'pos': 'noun',
+      'hanja': ['學校'],
+      'senses': [
+        {
+          'glosses': ['school'],
+          'info': [definition],
+        },
+      ],
+    });
+    final read = entries.singleWhere((entry) => entry['headword'] == '읽다');
+    expect(read['reading'], '익따');
+    expect(read['textKeys'], containsAll(['읽다', '읽어', '읽고']));
+    expect(
+      (read['entry']! as Map)['inflections'],
+      contains(equals({'text': '읽어'})),
+    );
+    final together = entries.where((entry) => entry['headword'] == '같이');
+    expect(
+      [for (final entry in together) (entry['entry']! as Map)['pos']],
+      ['particle', 'adv'],
+    );
+  });
+
+  test('an idiom or a proverb is an entry of its own, never found in running '
+      'text, with an id told apart from its word', () async {
+    final [_, ...entries] = await converted();
+
+    final proverb = entries.singleWhere(
+      (entry) => entry['headword'] == '가는 날이 장날',
+    );
+    expect(proverb['id'], '27500:가는 날이 장날');
+    expect((proverb['entry']! as Map)['pos'], 'proverb');
+    expect(proverb.containsKey('textKeys'), isFalse);
+    expect(
+      entries.singleWhere((entry) => entry['headword'] == '가다')['id'],
+      '27500',
+    );
+  });
+
+  test("Wiktionary's forms find a word in text; a verb rarely written as "
+      'the dictionary writes it ranks by its most used form', () async {
+    final korean = WiktionaryKorean()..forms['가다'] = {'가요', '갔어요', '갑니다'};
+    final [_, ...entries] = await converted(
+      korean: korean,
+      frequencies: WordFrequencies(const {'갔어요': 50}),
+    );
+
+    final go = entries.singleWhere((entry) => entry['headword'] == '가다');
+    expect(go['textKeys'], containsAll(['가다', '가요', '갔어요']));
+    expect(go['labels'], contains('common'));
+    expect(go['rank'], 100000 + 100);
+  });
+
+  test("the export's JSON download is the third its page offers", () {
+    expect(
+      krdictJsonDownloadOf('''
+        <button onclick="batchDownload('215')">엑셀</button>
+        <button onclick="batchDownload('216')">XML</button>
+        <button onclick="batchDownload('217')">Json</button>'''),
+      '217',
+    );
+    expect(krdictJsonDownloadOf("batchDownload('0')"), isNull);
+  });
+}