The CheckSystem workflow sends a 'PASSED!' SendActivity when all system
variables are populated, producing 1 AgentResponseEvent. The test case
had min_response_count: 0 with no max, so the assertion defaulted max
to 0 and failed with 'Response count greater than expected: 0 (Actual: 1)'.
Updated to expect exactly 1 response, matching the SendActivity pattern.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>