feat(i18n): add Simplified Chinese (zh-CN) locale

Add a complete zh-CN catalog covering all 800 leaf keys in en.json, with an
identical key set and key order so catalog integrity holds unchanged.

- add asyar-launcher/src/locales/zh-CN.json
- register the catalog under both `zh-CN` and the base tag `zh`, so regional
  variants (e.g. zh-Hans) resolve to Simplified Chinese rather than falling
  back to English
- list zh-CN in the catalog integrity test and generalise the key-parity
  assertion to run against every translated catalog
- cover zh-CN resolution (zh-CN / zh-Hans / zh) in the i18n service tests

Brand names, keyboard notation and placeholders ({title}, {query},
{argument}, {clipboard}, {date}) are preserved verbatim.

Author: 党飞飞