HTML Architect: E2E tests - run the integration suite single-worker locally + trim local timeouts

Hi all,

A small QoL improvement for the architect-html Playwright integration suite.

Locally the suite runs tests in parallel, but they all share one real backend that holds state across the whole process. That means parallel tests can interfere with each other and fail in ways that look random. In CI it’s fine, because there the suite already runs single-worker.

I’d suggest two changes:

Run the suite single-worker locally too, matching CI. The tests are backend-bound anyway, so the parallelism isn’t buying much.
Reduce the timeouts for local runs, keeping the generous ones for CI where DB and backend startup are genuinely slower.

I’m happy to open a PR for this.

Thanks!