Wire manifest, apple-touch-icon, and web-app meta tags into index.html
Add the PWA <link>/<meta> tags to index.html so the document is fully
installable, with a regression test asserting they are present.
Also add "node" to the tsconfig types array so the PWA test file's
node:fs / node:url imports typecheck — these imports were introduced in
the icons task but the tsconfig was never updated, leaving npm run
typecheck failing on tests/pwa.test.ts.