[sanskarIN]

Purpose

Continue #70 by removing the second, legacy VitePress implementation of canonical URL and locale metadata. All public URLs and SEO tags now derive from the same Scarp-owned routing contract used to render the production site.

Changes

• Add a framework-independent scripts/scarp-site/seo.ts for canonical, reciprocal English/Hindi hreflang and Open Graph metadata, with safe HTML attribute escaping; use it in the real HTML renderer.
• Add urlForPage to the existing route contract and migrate sitemap, built-page, unit and live-site validators away from docs/.vitepress/site-meta.ts.
• Expand the real Pages smoke matrix to test the latest published compiler release in both locales as well as historical alpha.1 routes.
• Remove the now-unused legacy URL helper and adjust the dormant VitePress configuration to import metadata from the independent engine.
• Strengthen SEO/build tests to detect missing or duplicate exact metadata tags; preserve the complete 142-page bilingual sitemap coverage.

Acceptance

All eight repository CI jobs including independent browser/offline and six tagged compiler conformance jobs must pass before merge. Do not publish stable docs or change historical compiler evidence. Manual assistive-technology review remains #65.