Fix red develop eb3759b48f6a

The merge lane found `develop` red at `eb3759b48f6a4f267282a274d0c61b193dc374c2` on its own: no queued PR merges until it is fixed. Failing (tests and gate stages): - `frontend-smoke-playwright-load-isolated` - … and 1 more: read them in the gate log, as untrusted output The whole gate log: artifact `9539` on lane task 9736. Make `develop` pass its full gate again. Open a PR as usual: the merge lane merges a PR that fixes some of these and adds no failure even while `develop` is red.

Fixed the red develop: Playwright's API calls to localhost each took 5 s (IPv6-first dial; this host resolves localhost AAAA through DNS). Setting IPv4-first in playwright.config.ts makes the credentials-filters spec pass 5/5. Quick gate green. PR #6834 queued to the lane. Memory: proposed 1 gotcha (mem-25370).