T-1190: step-canvas wire staleness signal + client sim_ttl threading (the D-253 clock seam raised in PR #204 review, adjudicated future-seam). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
T-1190: step-canvas wire staleness signal + client sim_ttl threading (the D-253 clock seam raised in PR #204 review, adjudicated future-seam). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>