fix(build): stub cloudflare:* imports while prerendering in Node (#3319)

[Divkix]

Fixes #3319

Summary

vinext build --prerender-all (and vinext-cloudflare deploy --prerender-all) renders routes by starting a Node production server against the built output. A Cloudflare target builds a Worker bundle that keeps cloudflare:* imports external - only workerd resolves them - so importing that entry under Node died with ERR_UNSUPPORTED_ESM_URL_SCHEME before a single route rendered, even for apps whose prerendered routes never touch a binding.

• Prerender-purpose servers now register node:module loader hooks that resolve every cloudflare:* specifier to one inert stub module: the scoped helpers run their callback, waitUntil is dropped, and reading env/exports/cache/tracing throws a message naming the cause, so a binding-dependent route fails per-route instead of taking the whole build down.
• Serving servers are untouched and the deployed bundle still imports the real modules - the hooks live only in the Node prerender process (all five prerender entry points already pass purpose: "prerender").
• Chose stubbing over executing the prerun under workerd/miniflare (both options are listed in the issue): stubbing keeps the existing Node harness that per-route static generation already uses and adds no new runtime dependency, while still failing loudly for routes that genuinely need bindings.

Test plan

• tests/prerender-workerd-stubs.test.ts - drives the loader hooks and the stub surface directly (resolve/load short-circuit, binding reads throw, probes stay inert, exported names).
• tests/prerender-cloudflare-bindings.test.ts - runs the real CLI (vinext build --prerender-all) against tests/fixtures/cf-prerender-bindings, whose server graph imports cloudflare:workers; asserts the prerendered routes exist and that dist/server/index.js still keeps the import external.
• Local CI-equivalent run: vp run build, vp run check, vp run knip, bash syntax + shard manifest, vitest unit + integration, response-store e2e, create-next-app/create-vinext-app jobs, and the Playwright projects. The only local failures were a build-hash-dependent action-id assertion (fails with and without this change) and e2e specs whose fixed ports were held by another worktree on the same machine.

[pkg-pr-new]

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@vinext/cloudflare

npm i https://pkg.pr.new/@vinext/cloudflare@3332

create-vinext-app

npm i https://pkg.pr.new/create-vinext-app@3332

@vinext/types

npm i https://pkg.pr.new/@vinext/types@3332

vinext

npm i https://pkg.pr.new/vinext@3332

@cloudflare/workers-response-store

npm i https://pkg.pr.new/@cloudflare/workers-response-store@3332

commit: 6fcbd14

[github-actions]

Performance benchmarks

Compared 6fcbd14 against base e97de29 using alternating same-runner rounds. Next.js was unchanged and skipped.

0 improved · 0 regressed · 6 within ±1.5%

Scenario	Framework	Baseline	Current	Change
Client bundle size (gzip)	vinext	142.2 KB	142.2 KB	⚫ +0.0%
Client entry size (gzip)	vinext	129.6 KB	129.6 KB	⚫ +0.0%
Dev server cold start	vinext	3.12 s	3.13 s	⚫ +0.2%
Production build time	vinext	3.64 s	3.63 s	⚫ -0.1%
RSC entry closure size (gzip)	vinext	121.0 KB	121.0 KB	⚫ -0.0%
Server bundle size (gzip)	vinext	218.3 KB	218.3 KB	⚫ +0.0%

View detailed results and traces

_{🟢 improvement · 🔴 regression · ⚫ change below 1.5% · paired base/head}