Pages Router prerender: pages under `/api-...` and lazy catchall pages never finish loading

This issue was created by an agent analysing CI failures from the Next.js Deploy Suite (vinext main vs Next.js v16.2.6, 2026-05-22).

Problem

Pages whose path begins with /api-docs/... (an apparent false positive of API-route detection) and lazy fallback catch-all pages (fallback: true) hang waiting for the rendered content. The fallback boundary stays on fallback text and never resolves to the page contents.

page.waitForSelector('#api-docs') timeout

TIMED OUT: /Hi.*?delayby3s/

Estimated Impact

~3 test failures across the deploy suite.

Affected Test Suites

• test/e2e/prerender.test.ts (3 failures)

Recommendation

1. Reproduce first in vinext's own test suite. Add a Pages Router page at pages/api-docs/index.tsx and a [...slug] lazy catchall. Verify each finishes loading.

2. Tighten API-route detection. Match only pages/api/... (with the slash), not the substring api-. Otherwise pages whose path starts with api- are treated as API routes and never render.

3. Resolve the fallback for lazy catchall. Make sure the prerender fallback resolves to the rendered content once getStaticProps completes.

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Part of #1328.