feat(site): redesign the ForgeKit landing page

[CodeWithJuber]

Summary

• replace the delayed, jsDelivr-pinned landing SPA shell with repository-owned HTML, CSS, and a small dependency-free interaction layer
• introduce a bespoke warm editorial / technical-instrument design that explains memory, foresight, guardrails, protocol flow, supported tools, evidence, and beta limits
• add accessible keyboard tabs, reduced-motion handling, copyable install modes, responsive 390 px behavior, and immediate first paint
• keep visible and structured-data versions wired into forge bump; keep benchmark claims, brand tokens, metadata, and Pages assets under tests
• refresh the generated architecture map and changelog

Validation

• node --test test/pages.test.js test/bump.test.js — 37 passed, 1 optional integration skipped
• repository suite excluding the two loopback-network files blocked by this sandbox — 1,044 passed, 2 optional checks skipped
• npm run check — passed (existing repository warnings only)
• npm run typecheck
• npm run pages:build
• node src/cli.js docs check
• git diff --check
• browser-reviewed the production-static page at desktop and 390 px; capability and install interactions verified
• core contrast pairs: AA/AAA

Delivery notes

The landing now loads no external JavaScript, framework runtime, CDN chunk, or webfont. GitHub Pages copies only the page and its readable local app.js, alongside the existing brand assets.