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>

halkyon_learn_curator/test/tatoeba_test.dart

@@ -1,133 +0,0 @@
-import 'dart:convert';
-import 'dart:io';
-
-import 'package:halkyon_learn_curator/src/sources/cedict.dart';
-import 'package:halkyon_learn_curator/src/sources/tatoeba.dart';
-import 'package:halkyon_learn_curator/src/sources/wiktionary.dart';
-import 'package:test/test.dart';
-
-void main() {
-  late Directory into;
-
-  setUp(() => into = Directory.systemTemp.createTempSync('tatoeba'));
-  tearDown(() => into.deleteSync(recursive: true));
-
-  Stream<String> lines(String fixture) =>
-      File('test/fixtures/$fixture')
-          .openRead()
-          .transform(utf8.decoder)
-          .transform(const LineSplitter());
-
-  /// [file]'s lines with the fixtures' sentences of [code] as examples.
-  Future<List<Map<String, Object?>>> enriched(File file, String code) async {
-    final links = await readTatoebaLinks(lines('tatoeba-$code-eng_links.tsv'));
-    final sentences = await readTatoebaSentences(
-      lines('tatoeba-${code}_sentences.tsv'),
-      wanted: links.containsKey,
-    );
-    final linked = {for (final ids in links.values) ...ids};
-    final translations = await readTatoebaSentences(
-      lines('tatoeba-eng_sentences.tsv'),
-      wanted: linked.contains,
-    );
-    return [
-      for (final line in await withTatoebaExamples(
-        file,
-        sentences: sentences,
-        translations: translations,
-        links: links,
-      ).join().then((text) => text.split('\n')))
-        if (line.isNotEmpty) jsonDecode(line) as Map<String, Object?>,
-    ];
-  }
-
-  List<Map<String, Object?>> examplesOf(Map<String, Object?> line) => [
-    for (final example
-        in ((((line['entry']! as Map)['senses']! as List).first
-                    as Map)['examples']
-                as List? ??
-            const []))
-      example as Map<String, Object?>,
-  ];
-
-  test("a German word's sentences come first in its first sense, those "
-      'without a translation left out, the header crediting Tatoeba', () async {
-    final [german, ...] = await wiktionaryDictionaries(
-      lines('wiktionary-sample.jsonl'),
-      into: into,
-      sourceVersion: '2026-10-03',
-      languages: {'de'},
-    );
-
-    final result = await enriched(german, 'deu');
-
-    expect([
-      for (final credit in result.first['credits']! as List)
-        (credit as Map)['name'],
-    ], contains('Tatoeba'));
-    final haus = result
-        .skip(1)
-        .singleWhere((line) => line['id'] == 'Haus/noun');
-    final examples = examplesOf(haus);
-    // Three of Tatoeba's, before Wiktionary's own.
-    // Those nearest seven words long first, then the shortest.
-    expect(examples.take(3).map((example) => example['tatoeba']), [
-      9984782,
-      1550095,
-      605418,
-    ]);
-    expect(examples.first['text'], 'Haus');
-    expect(examples.first['de'], 'Er ist im Haus.');
-    expect(examples.first['en'], isA<String>());
-    expect(examples[3]['de'], 'In dem Haus haben wir mal gewohnt.');
-    // A form finds its word: aß is essen's.
-    final essen = result
-        .skip(1)
-        .singleWhere((line) => line['id'] == 'essen/verb');
-    expect(examplesOf(essen).first['text'], 'aß');
-  });
-
-  test(
-    'Chinese sentences are cut by the longest words the dictionary has',
-    () async {
-      final file = File('${into.path}/cc-cedict-hans-en.jsonl');
-      await file.writeAsString(
-        cedictDictionary(
-          await File('test/fixtures/cedict-sample.txt').readAsString(),
-          traditional: false,
-        ).join(),
-      );
-
-      final result = await enriched(file, 'cmn');
-
-      final xuexi = result
-          .skip(1)
-          .singleWhere((line) => line['id'] == '學習 学习 [xue2 xi2]');
-      expect(examplesOf(xuexi), isNotEmpty);
-      expect(examplesOf(xuexi).first['text'], '学习');
-      expect(examplesOf(xuexi).first['zh-Hans'], contains('学习'));
-    },
-  );
-
-  test('Korean words are found with their particles taken off', () async {
-    final [korean, ...] = await wiktionaryDictionaries(
-      lines('wiktionary-sample.jsonl'),
-      into: into,
-      sourceVersion: '2026-10-03',
-      languages: {'ko'},
-    );
-
-    final result = await enriched(korean, 'kor');
-
-    final home = result.skip(1).singleWhere((line) => line['id'] == '집/noun/1');
-    expect(examplesOf(home), isNotEmpty);
-    expect(examplesOf(home).first['text'], '집');
-    expect(examplesOf(home).first['ko'], contains('집에서'));
-  });
-
-  test("Tatoeba's codes of the languages", () {
-    expect(tatoebaCode('de'), 'deu');
-    expect(tatoebaCode('zh-Hant'), 'cmn');
-    expect(tatoebaCode('ja'), isNull);
-  });
-}