[sanskarIN]

Closes the Phase 1 implementation milestone of #70 (does not close the full migration issue).

Introduces a self-owned docs engine

• New scripts/scarp-site/ TypeScript generator parses the existing Markdown/YAML pages using focused data parser libraries, not VitePress/Vue as site renderer.
• Generates 138 English/Hindi HTML pages at exact existing public clean routes, reciprocal canonical/hreflang metadata, Open Graph URL, sitemap, and local bilingual search index.
• Custom Scarp design system with responsive sidebar, homepage features, dark/light, language switch, accessible local-search dialog, syntax-highlighted Scarp examples, release-aware Command Finder, and opt-in deployment history.
• Escapes author-provided HTML by default; supported callout and widget markup is injected through explicit owned rendering adapters; no client framework or bundler (browser TS compiled by TypeScript directly).
• Introduces independent scarp:build and scarp:test commands with 138-route/static/Unicode/XSS/release-parity assertions, and adds these to PR CI.

Safety / non-goals of this PR

This is a shadow build only: generated output is artifacts/scarp-engine-preview/scarp-docs/ and excluded from Git. VitePress is still used by the live Pages workflow, offline archive and older tests until the custom site passes a separate real-browser parity and production migration gate. No stable release and no compiler semantic changes.

Track the full VitePress removal, deployed-site switch and cleanup under #70. All existing compiler-tagged conformance jobs must stay green.