SvelteKit 2, with the Vite 5 toolchain it needs (supersedes #176)

[xuelink]

Replaces #176. Dependabot bumped @sveltejs/kit to 2 and @sveltejs/adapter-static to 3 on their own, and its CI failed at npm install (ERESOLVE): Kit 2 needs Vite 5, the repo was on Vite 4, and vitest 0.32 pinned Vite 4 through vite-node. This PR does the whole step.

Versions

Package	Before	After
@sveltejs/kit	1.30.4	2.70.3
@sveltejs/adapter-static	2.0.3	3.0.10
@sveltejs/vite-plugin-svelte	(via Kit)	3.1.2, now a direct dependency
vite	4.5.12	5.4.21
vitest	0.32.4	3.2.7
typescript	5.2.2	5.9.3
svelte-check	3.5.2	3.8.6
devalue (what #176 was about)	4.3.2	5.9.4
@types/node	20.8.7, via vitest 0.32	20.19.43, a direct dev dependency

Svelte stays on 4.2.19; vite-plugin-svelte 3 is the line that supports it. sass stays on 1.69.4.

Code — two changes from the migration guide, the rest do not apply here (no cookies, goto, $env/dynamic, $app/paths, hooks, form actions or top-level promises in a load):

• svelte.config.js imports vitePreprocess from @sveltejs/vite-plugin-svelte.
• The nine throw error(...) in the tools loaders drop the throw.

Checks

• npm run check: 0 errors (warnings went from 8 to 2; the newer svelte-check knows text-wrap and container-type).
• vite build before and after: the same 1,371 pages and 5,278 other files. Every static file is byte-identical. Every page's HTML is identical once scripts, stylesheet links and hashes are set aside. The CSS each page loads has the same rules; only the asset hash format changes, and the newer esbuild writes rgba(255,255,255,.25) as the equivalent #ffffff40.
• A fresh npm install from the new lockfile in an empty folder, as CI does it, resolves with no conflicts.
• Full npm run build (image optimisation and sitemap) under Node 20, the CI version.
• In the browser on the Vite 5 dev server: the homepage hydrates, the guess game and FAQ respond, the theme toggle cycles, client-side navigation from the header works, the /compare picker switches apps, /plans, a comparison post and /tools/say/hello render, with no console errors.

Notes

• The first CI run failed svelte-check with 25 errors: vitest 0.32 had brought @types/node in, vitest 3 does not, so node:path and node:fs/promises went untyped. It passed locally because the worktree sits inside the main checkout and TypeScript found the types in the parent's node_modules. The second commit adds @types/node 20 directly, and the whole CI job (clean npm install, npm run check, full npm run build) was then re-run under Node 20 in a copy outside the checkout: 0 errors, 1,371 pages, output identical to the local build.
• npm cannot move Kit, adapter-static and Vite together from the old lockfile (it checks each new peer against the version still installed), so the lockfile was produced with --legacy-peer-deps and then re-run with a plain npm install; npm ls --all is clean.
• pnpm-lock.yaml is left alone. It was already stale (no posthog-js, gsap or three) and npm is what CI and the deploy use.
• npm run build fails on Node 24 in the image-transmutation postbuild step (its esm loader breaks). That is unrelated to this change and does not affect CI, which runs Node 20.

🤖 Generated with Claude Code