e2e-tests

Write or fix a Playwright end-to-end test in frontend/e2e — a new journey spec, a seeded fixture, or debugging "the e2e suite passes but the feature is broken" / "make test-e2e fails". Use for any spec that crosses the whole stack (sign in, build an agent, publish, run, approve). Every page in this product renders its empty state when a query fails, so a spec that asserts on chrome is a spec that asserts on nothing.