feat(curator): KANJIDIC2 and the kana as a dictionary of characters; KanjiVG's strokes for the app

A dictionary file now says whether it holds words or characters (`kind`).
The kanjidic adapter turns KANJIDIC2 into one entry per kanji that has a
Japanese reading or an English meaning (12,633), with its readings,
meanings, school grade, strokes, frequency and JLPT level (Jonathan
Waller's, through kanji-data's kanji.json), labelled `jlpt:nX`,
`grade:N`/`grade:secondary`, followed by the 71 hiragana and katakana of
the kana table with their romaji. A kun reading is found whole; its kanji
part only as a loose key, so typing "ta" brings た before every kanji read
so.

`curate kanjivg` writes KanjiVG's strokes and components as the app's
stroke files, one gzipped JSON file per 256 code points, keyed by the code
point in each entry's id (KanjiVG's 橅 names itself 機).

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_curator/pubspec.yaml

@@ -11,6 +11,7 @@ resolution: workspace
 
 dependencies:
   args: ^2.7.0
+  xml: ^7.0.1
 
 dev_dependencies:
   test: ^1.25.5