5c5f9953

By: Michael Lynch <git@mtlynch.io>

Make e2e-tests derivation deterministic

Replace the installPhase block that copies Playwright run artifacts
(traces, videos, reports) into $out with a simple result marker file.
The copied artifacts vary between runs, causing `nix build .#e2e-tests
--rebuild` to fail with a nondeterministic output error.

Co-authored-by: Shelley <shelley@exe.dev>