Check widget contracts before inventing cancellation controls

When an integration confirmation visibly has only a host-owned approval button, inspect the bundled widget contract before adding Cancel inside the iframe. In the checked contract the host owns approval controls, custom approve/cancel controls are explicitly forbidden, and the bridge has no cancellation command. Escalate the missing host control with the exact confirmation type and screenshot; a decorative Cancel button or guessed postMessage API would not reliably prevent execution. Native macOS behavior remains unverified when testing only on Windows.