fix(cloudflare): skip regex literals when rewriting top-level returns in frontmatter

[lazerg]

Changes

• The dep-scan plugins for .astro files rewrite top-level return to throw so esbuild/Rolldown accept the frontmatter as an ES module. They found those return keywords with a single regex whose skip group covered strings, template literals and comments, but not regex literals. A quote inside a regex literal, as in value.replace(/"/g, """), was then read as an opening string delimiter, so quote pairing stayed off by one for the rest of the frontmatter and every later top-level return was left alone. Vite reported Failed to run dependency scan plus one Top-level return cannot be used inside an ECMAScript module per surviving return, and only on a cold node_modules/.vite, which made it look intermittent.
• replaceTopLevelReturns now scans the frontmatter character by character instead. It skips strings, template literals, line and block comments, and regex literals, and only rewrites a return found in code. A / is treated as the start of a regex literal only when the preceding token allows an expression there, so division is left alone.
• Moved the helper to src/utils/frontmatter.ts, since the esbuild and Rolldown plugins each carried their own copy of the same tokenizer and the same bug.

Closes #17697

Testing

Added test/frontmatter-returns.test.ts covering the reported case along with division, character classes, member access, strings and comments. The regex-literal case fails on main and passes here. The existing top-level-return integration test still passes.

Docs

No docs needed, this only fixes the dependency scan for frontmatter that was already valid.

[changeset-bot]

🦋 Changeset detected

Latest commit: eec3bd6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 44 packages

Name	Type
@astrojs/cloudflare	Patch
@test/astro-cloudflare-node-prerender-mdx	Patch
@test/astro-cloudflare	Patch
@test/astro-cloudflare-allowed-hosts	Patch
@test/astro-cloudflare-astro-dev-platform	Patch
@test/astro-cloudflare-astro-env	Patch
@test/astro-cloudflare-binding-image-cache	Patch
@test/astro-cloudflare-binding-image-service	Patch
@test/astro-cloudflare-cache-provider-wait-until	Patch
@test/astro-cloudflare-cache-provider	Patch
@test/astro-cloudflare-client-address	Patch
@test/astro-cloudflare-compile-custom-image-service	Patch
@test/astro-cloudflare-compile-image-service	Patch
@test/astro-cloudflare-custom-entryfile-fetch-state	Patch
@test/astro-cloudflare-custom-entryfile	Patch
@test/astro-cloudflare-custom-image-service	Patch
@test/astro-cloudflare-dev-image-endpoint	Patch
@test/astro-cloudflare-external-image-service	Patch
@test/astro-cloudflare-external-redirects	Patch
@test/cloudflare-incremental-images	Patch
@test/astro-cloudflare-internal-redirects	Patch
@test/astro-cloudflare-no-output	Patch
@test/astro-cloudflare-prerender-node-env	Patch
@test/astro-cloudflare-prerender-queue-consumers	Patch
@test/astro-cloudflare-prerender-styles	Patch
@test/astro-cloudflare-prerenderer-errors	Patch
@test/astro-cloudflare-prerenderer-render-error	Patch
@test/routing-priority-cloudflare	Patch
@test/cf-server-entry	Patch
@test/astro-cloudflare-server-island-prerender-framework	Patch
@test/astro-cloudflare-sessions	Patch
@test/astro-cloudflare-sql-import	Patch
@test/cf-ssr-deps	Patch
@test/astro-cloudflare-static	Patch
@test/astro-cloudflare-svelte-rune-deps	Patch
@test/astro-cloudflare-top-level-return	Patch
@test/cf-user-optimize-deps	Patch
@test/astro-cloudflare-vite-plugin	Patch
@test/astro-cloudflare-with-base	Patch
@test/astro-cloudflare-with-react	Patch
@test/astro-cloudflare-with-solid-js	Patch
@test/astro-cloudflare-with-svelte	Patch
@test/astro-cloudflare-with-vue	Patch
@test/astro-cloudflare-wrangler-preview-platform	Patch

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