Review and fix test suites and CI failures

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.

Reviewed 80 CI runs: past reds already fixed. Fixed the one live red on develop (project tab-fit e2e after the Budget-tab change) and cut five slow tests (11→1.6s, 4→1s, 4→1.4s, 6×1.7→0.02s, 3→2s), mutation-checked. #6720 merged; deploy green. Memory: none applied.