adds ko-KR な to にゃ (#3820)

* adds ko-KR な to にゃ
- this only take considers pre-composed "Hangul Syllables",
not composable area "Hangul Jamo" which are not used commonly
- 56 is '냐' - '나'

* replace magic number as suggested

src/models/note.ts

@@ -372,7 +372,14 @@ export const pack = async (
 	//#endregion
 
 	if (_note.user.isCat && _note.text) {
-		_note.text = _note.text.replace(/な/g, 'にゃ').replace(/ナ/g, 'ニャ').replace(/ﾅ/g, 'ﾆｬ');
+		_note.text = (_note.text
+			// ja-JP
+			.replace(/な/g, 'にゃ').replace(/ナ/g, 'ニャ').replace(/ﾅ/g, 'ﾆｬ')
+			// ko-KR
+			.replace(/[나-낳]/g, (match: string) => String.fromCharCode(
+				match.codePointAt(0)  + '냐'.charCodeAt(0) - '나'.charCodeAt(0)
+			))
+		);
 	}
 
 	if (!opts.skipHide) {