Astro's getRelativeLocaleUrl lowercases the locale segment by default, so landing links and hreflang for zh-CN, zh-TW, and pt-BR were emitted lowercase and 404 on case-sensitive Cloudflare Pages. Pin the casing at the localizeHref chokepoint with normalizeLocale: false, add an e2e hreflang casing guard, and add a deploy-time check that blocks the build if any lowercased locale path leaks into the output.
Closes#554
Shared Claude Code translation pipeline (scripts/i18n, no API key) plus Astro/VitePress/Scalar i18n wiring. Landing and API reference translated into all 20 languages; docs i18n wiring + English source anchors. The translated docs markdown (apps/docs/<locale>/**, 3,620 files) follows in a companion PR because it exceeds GitHub's per-PR CI file limit.
