Verification mechanism for the 20-run acceptance criterion of issue #553.
Triggered manually via workflow_dispatch, runs the full coverage suite 20×
in parallel against a single SHA, asserts zero `[birpc] rpc is closed`
lines in every cell.
One fire, parallel cost (~one main-job's wall-clock), deterministic signal
for the teardown race. Cheaper than 20 sequential push events and tests
the same property the AC names.
Closes the verification gap raised by Tobias and Elicit in the issue
discussion.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
c820884765