feat(curator): Chinese from CC-CEDICT, with the HSK levels of 2025

Chinese comes from CC-CEDICT (CC BY-SA 4.0), made for learners of
Chinese: `curate cedict` writes two dictionaries of its entries,
`cc-cedict-hans-en` (zh-Hans) and `cc-cedict-hant-en` (zh-Hant), so a
studyset finds its words as it writes them, each finding a word by
either script, by pinyin with or without tones and by its meanings.
Readings are pinyin with tone marks, a syllable to a character; measure
words are a remark beside the meanings.

The HSK levels are those of the 2025 examination syllabus, which HSK
3.0's examination follows since July 2026 (decided 2026-10-14: level
tags, credited), as hsk30 extracted them (MIT): `hsk:1` … `hsk:6`, and
`hsk:7` for 7 to 9, each given to the entry read as the syllabus reads
the word (的 de, not 的 dì; 书 shū, not the Book of Documents, Shū),
ranking the words, HSK 1 first.

`curate update --languages de,el,en,zh` takes over from `--wiktionary`:
Chinese from MDBG's file of the day as often as EDRDG's files, the rest
from Wiktionary's dump.

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/update_test.dart

@@ -178,4 +178,39 @@ void main() {
       expect(opened, 0);
     });
   });
+
+  test('CC-CEDICT is converted in both scripts with the HSK levels, and '
+      'said to be up to date by its files', () async {
+    expect(cedictUpdated(into), isNull);
+
+    final written = await updateCedict(
+      into: into,
+      data: Directory('data'),
+      fetch: (uri, file) async {
+        expect(uri, cedictSource);
+        await file.writeAsBytes(
+          gzip.encode(
+            File('test/fixtures/cedict-sample.txt').readAsBytesSync(),
+          ),
+        );
+      },
+    );
+
+    expect(
+      [for (final file in written) file.uri.pathSegments.last],
+      ['cc-cedict-hans-en.jsonl.gz', 'cc-cedict-hant-en.jsonl.gz'],
+    );
+    expect(header('cc-cedict-hant-en.jsonl.gz')['language'], 'zh-Hant');
+    expect(cedictUpdated(into), isNotNull);
+  });
+
+  test('Chinese comes from CC-CEDICT, the other languages from Wiktionary', () {
+    final all = dictionarySources({'de', 'el', 'en', 'zh'});
+    expect(all.wiktionary, {'de', 'el', 'en'});
+    expect(all.chinese, isTrue);
+    final traditional = dictionarySources({'zh-Hant'});
+    expect(traditional.wiktionary, isEmpty);
+    expect(traditional.chinese, isTrue);
+    expect(dictionarySources({}).chinese, isFalse);
+  });
 }