bd955696f9
Address all 4 remaining blocking issues from PR #7811 review: - Delete duplicate _validation_pipeline_mock.py in features/steps/ (the inline MockValidationExecutor is kept where it belongs) - Replace # type: ignore[return-value] with cast(dict[str, Any], ...) to satisfy the zero-type-suppressions policy for test additions - Add @tdd_issue_7623 regression tag on concurrency scenario - Remove unreachable dead-code RuntimeError guard in _install_thread_local_streams() (constructors never return None) All CI lint checks now pass. Source files remain within line limits.