* fix: use official Homebrew cask installation guidance
* docs: guide localized pages through the old Homebrew tap
The translated getting-started pages documented the official cask but not
the migration from the archived tap, so readers of those pages had no
uninstall step for the old formula.
- Replace the ambiguous Guide section with explicit overview, reference, and development routes while preserving legacy URLs with redirects
- Route missing localized content to maintained canonical pages and emit SEO alternates only for real translations
- Add parser-backed documentation integrity checks and make the optimized local build the default while retaining a complete production build
