Migrate webtools from Vite to client-side Next.js static export (GitHub Pages compatible)

[Copilot]

This PR converts apps/webtools from a Vite SPA to a fully client-side Next.js app, while preserving browser-only execution and static hosting on GitHub Pages. Routing remains hash-based in-browser, and generated metadata assets are still produced for runtime features.

• Framework/runtime migration (Vite → Next.js, client-only)

  • Replaced Vite entry/build scripts with Next.js (next dev, next build) in apps/webtools/package.json.
  • Added App Router shell (app/layout.tsx, app/page.tsx) and mounted the existing TanStack router through a client-only component (src/Nf2tApp.tsx), keeping navigation and route handling entirely in-browser.
  • Added Next TypeScript integration (next-env.d.ts, tsconfig plugin/include updates).

• Static export + GitHub Pages pathing

  • Added next.config.mjs with:
    • output: 'export'
    • trailingSlash: true
    • repo-aware basePath / assetPrefix under GitHub Actions
  • Updated Pages workflow artifact path from apps/webtools/dist to apps/webtools/out.

• Build-time generated browser assets

  • Replaced Vite plugin-based generated files with an explicit prebuild script: scripts/generateStaticFiles.mjs.
  • Script writes public/buildinfo.json and public/nars.json before next build, preserving existing runtime fetch behavior.
  • Added resilient fallback for NAR metadata generation when remote download is unavailable.

• Documentation/UI alignment

  • Updated build-process route copy (buildInfo.lazy.tsx) to describe Next.js workflow and entrypoints instead of Vite-specific internals.

// apps/webtools/next.config.mjs
const nextConfig = {
  output: 'export',
  trailingSlash: true,
  basePath,
  assetPrefix: basePath || undefined,
  images: { unoptimized: true },
};

• Fixes Convert to NextJS #1