i18n: Simplified Chinese (zh-hans) interface catalog

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.

NOTICE

@@ -31,8 +31,9 @@ WebAssembly plug-ins run in the wasmi interpreter (MIT OR Apache-2.0); its wasmp
 under the Apache License 2.0 with the LLVM exception.
 
 Builds made with craft-fonts (the CRAFT_FONTS_DIR build option; all official releases) embed the
-fonts listed in https://github.com/storytold/craft-fonts/blob/main/ATTRIBUTION.md (today BIZ
-UDPGothic, Shippori Mincho and BIZ UDMincho; web builds BIZ UDPGothic Regular only) under the SIL
+fonts listed in https://github.com/storytold/craft-fonts/blob/main/ATTRIBUTION.md (BIZ UDPGothic,
+Shippori Mincho, BIZ UDMincho, Noto Sans CJK SC and Noto Sans Arabic in the current manifest;
+web builds BIZ UDPGothic Regular only) under the SIL
 Open Font License 1.1. Their license texts ship with the release packages as OFL-<family>.txt.
 
 PDF import decodes CJK text with Adobe's CMap resources (https://github.com/adobe-type-tools/cmap-resources),