docs: add categorized milestone table to Home and Japanese plan translations Home.md/Home_ja.md now list all eight registered milestone plans (M2-M9) grouped by area, with date, status, tracking issue link, and a language cross-link, matching the format used in the vsextensionforcodex wiki. Each plan page gains a _ja.md counterpart (none existed before). Home also gains a curated Microsoft Learn reference section grouped by milestone area, covering the Win32/COM/ MSVC surface these plans implement. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>