Adds the German locale per maintainer guidance in issue #1980.
- docs/de-DE/README.md: full translation of the English root README
- docs/de-DE/GLOSSARY.md: German terminology decisions (which ECC
terms stay English vs. German)
- manifests: docs-de-de module + locale:de-de component, modelled on
the existing docs-zh-tw / locale:zh-tw entries
- scripts/lib/install-manifests.js: de-DE in SUPPORTED_LOCALES, plus
de-DE and de aliases so `--locale de` and `--locale de-DE` resolve
- tests/lib/locale-install.test.js: focused de-DE coverage
- Deutsch added to the language selector tables in all 10 existing
READMEs (root + 9 localized)
Refs #1980
Adds docs/th/README.md with a concise onboarding-style Thai
translation mirroring the docs/vi-VN format. Updates the language
switchers in the English, Simplified Chinese, Traditional Chinese,
Japanese, Korean, Portuguese (BR), Russian, Turkish, Vietnamese,
and Simplified Chinese docs READMEs to link to the new Thai page.
The English README remains the canonical source of truth; the Thai
page links back to it for full content.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
