Test suite cleanup and CI fix

Review all test suites, delete stale, superseeded, those that were one off to check feature flags or absence of something. Kill the most long running or flaky with unit tests that execute in milliseconds. Regroup between quick and full, Fix broken tests in CI - GitHub Actions - look at a few recent test runs and fix broken/flaky tests. Babysit CI/CD until the tests (test.yaml) pass.

PR #6497 merged (42404dd0f), Jaah Deploy green. Fixed the one open CI failure (live-cast e2e race); 8 real-time vitest waits now take ms (3 mutants killed); 5 stale tests + 9 ghost probes deleted. Deferred: markdown h1 in artifact preview; test.yml awaits next promotion PR. Memory: proposed 1 gotcha.