chore: declare e2e coverage variants in one place

[Nic-Polumeyv]

A coverage variant such as SVELTE_ASYNC or ROUTER_RESOLUTION is declared once, in the app's playwright.config.js through configure(); KIT_E2E_VARIANT selects it per run, and CI rows carry it as data next to project and shard. The per-variant scripts at three layers go, and webServer.env is no longer hand-written per app. Coverage is unchanged: playwright test --list per row is identical up to the project-name suffix. The basics server spec from #16872 runs as its own server:dev and server:build rows instead of inside every basics leg, so the matrix has 28 rows. Which rows run, and with which variant, is a row edit from here: #16861.

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 3c97241:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/3c97241bb4543b6c8fd3a4bf78ebd97733bee076

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16845

[changeset-bot]

⚠️ No Changeset found

Latest commit: 3c97241

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-16845-svelte.vercel.app/