Auto-diagnose test gaps from file changes and track test outcomes

Notes & tips

• Depend on the documented public surface. test_maintenance gives you TestMaintenanceWorkflow, TestMaintenancePlan, TestPlanItem, TestAction, and TestPriority. test_runner gives you run_tests_with_tracking, track_coverage, track_file_tests, get_file_test_status, and get_files_needing_tests. Names with a leading underscore are internal and may change.
• Preview with dry_run before executing. Both "execute" and "auto" modes accept dry_run=True, which reports what would run without touching anything — the cheapest way to sanity-check a plan.
• Pass changed_files for event-driven runs. Supplying the files that changed refreshes the index and focuses the plan, instead of re-evaluating the whole project.