The plan for this build was written to docs/plans/ only after Step 0's
implementation had already started, instead of as its own first action
right after ExitPlanMode. CLAUDE.md said *where* to save plans but not
*when* relative to other work, so that ordering wasn't actually enforced.
Makes it explicit: copying the plan into docs/plans/ and committing it is
its own checkpoint that blocks starting Step 0.
Also adds a docs/plans-executions/ convention: one running, chronological
summary file per plan, appended to after each completed step, for a
human-readable narrative of how the plan actually went (judgment calls,
spec gaps, surprises) without duplicating the plan or the diff.
Backfills the Step 0 entry for the proxy-operator plan retroactively.
Co-Authored-By: Claude <noreply@anthropic.com>