Add static site generator, responsive UI & i18n, translation proxy, and cache-busted assets

[K1SysAdmin]

Motivation

• Provide a repeatable, dependency-free build for the GitHub Pages site instead of hand-editing generated HTML.
• Improve accessibility and frontend UX by adding skip-links, a responsive visual refresh, theme controls, and a language switcher.
• Enable basic localization and an optional secure machine-translation path while ensuring deployable assets are cache-busted.

Description

• Add a minimal static site generator scripts/build_site.py and a validator scripts/check_site.py, plus site/site_manifest.json and site/templates/page.html to drive generation.
• Introduce a full frontend refresh: docs/assets/site.css (large responsive + theme + RTL updates) and docs/assets/site.js (theme, locale, search, audience pathways, and machine-translation UI).
• Add i18n catalogs (site/i18n/ar.json, docs/assets/i18n.ar.json), source Markdown content under source/quartz-content-vault/, and many regenerated docs/**/*.html pages updated to use cache-busted asset references (query ?v=2026-06-27-commit6) and accessibility anchors (`id=

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Codex Task