chore: run the cross-platform and async dev e2e legs on pushes only

[Nic-Polumeyv]

Every pull request runs all 31 legs from #16845, about 110 runner-minutes against the org's 20 concurrent job cap (5 for macOS), so a burst of PRs queues longer than the jobs take. Two groups rarely change a PR's outcome: the six cross-platform legs (windows, firefox, webkit on macOS) and the three async dev legs, which exercise a compiler flag plus one define that behave the same in dev and build. The two resolution no-js legs duplicate the base no-js legs outright, since nothing requests __route.js without JS.

This drops the two duplicates and moves the nine others into an e2e-push job with if: github.event_name == 'push', sharing env and steps with e2e through YAML anchors (an exclude cannot filter an include-only matrix). A pull request runs 22 jobs, about 65 runner-minutes; a push to version-3 still runs everything. Listing the tests per matrix row with playwright test --list before and after shows no test is absent from every PR row, and every push-only test still runs on push.

e2e-push has only been observed skipping on pull_request runs; the first push after merge is the check that it materialises.

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from cf06113:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/cf061130658f0c9d3a3d137c26ca5f8d6f12e8db

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16861

[changeset-bot]

⚠️ No Changeset found

Latest commit: cf06113

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-16861-svelte.vercel.app/