chore: inspect platform builds before deployment

[teemingc]

This PR runs build.test.js when present immediately after building so inspection failures block deployment. It also removes the build artifact download from the end-to-end job, leaving build inspections in the pre-deployment stage.

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 8cb059d:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/8cb059d5ce29ae5ace0eed71e826eb3ce08b0ebd

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/17367

[changeset-bot]

⚠️ No Changeset found

Latest commit: 8cb059d

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-17367-svelte.vercel.app/

[teemingc]

Platform test failures are Netlify bugs. One’s already fixed in the Netlify CLI but won’t be applied until 2 days have passed the minimum release age rule