The zh-hans catalog, registered as 简体中文: zh-CN, zh-SG, zh-Hans-* and
a bare zh locale resolve to it (tested), and it claims complete menus.
NOTICE lists the craft-fonts faces of the current manifest (Noto Sans CJK
SC and Noto Sans Arabic were missing).
Landed from #303 (catalog, registration, locale tests and the NOTICE
line only). Its horizontal CJK composition, UI font fallback by weight,
dock, New Document, Brushes panel and preference-migration changes are
left for separate pull requests.