insights into workflow step profiling data

each step in the CLI execution is a 'workflow step', and contains profiling information about the start/end time and status of the step.

we should aggregate this information in order to understand what's failing where and why, see trends in workflow stage time, etc

No files, tests, or concrete entry points are named. Start by locating where the CLI records each workflow step's start time, end time, and status, then determine the intended aggregation and reporting scope. Done should make failures, workflow-stage time trends, and their causes understandable.

Written by the indexing model from the issue text.