ci: Windows clock and handle-probe diagnostics (do not merge)

Merged
BA
1d ago
+500-24

Diagnostic run for two intermittent Windows test failures. Not for merge.

Summary by cubic

Adds diagnostics for two intermittent Windows test failures, without changing runtime behavior. The mutation witness script now honors declared test run sets instead of running only the named failing test.

  • On DuplicateHandle error 50, resolves the child's handle type via NtQueryInformationProcess/NtQueryObject and prints it; the exemption is narrowed to EtwRegistration object types only, never File or Pipe, with live ETW and real-pipe probe tests.
  • Adds a Windows test sampling 512 entered 30 ms burns, printing GetThreadTimes, QueryThreadCycleTime, QPC counters and thread id, and asserting paused CPU time is unchanged.
  • Adds mutation controls that break leave() bookkeeping and the nonduplicable-handle exemption to confirm the guards catch them.
  • The witness script runs exact test sets or filters, requires all declared siblings to execute and pass, and records baseline, applied-diff, mutant output and diff stats.