finish(STATE-WP-0064): cut over scheduler and split sweep errors from failures

STATE-WP-0064 cutover (state-hub only):
- Retire local custodian-sync.timer; archive units under infra/systemd/archived/
- Mark workplan finished; update infra/README, cron-migration, runbook, AGENTS.md
- Point activity-core-delegation at the consistency-sweep runbook

Consistency engine — automation error vs assessment failure:
- C-00 is an automation error; C-01..C-23 assessment failures are recorded
  for follow-up but no longer fail --remote --all scheduled sweeps (exit 0)
- Skip workplans/README.md in the workplan glob (human index, not a workplan)
- Progress events and compare script expose automation_error and
  assessment_failures separately from exit_code

infra/systemd/archived/README.md

@@ -0,0 +1,16 @@
+# Archived systemd units
+
+Retired 2026-06-21 as part of `STATE-WP-0064` cutover.
+
+The **State Hub consistency sync** schedule now runs on activity-core
+(Railiance01) via the `the-custodian.state-hub-consistency-sweep`
+ActivityDefinition. See [`docs/consistency-sweep-runbook.md`](../../../docs/consistency-sweep-runbook.md).
+
+These units are kept for reference or emergency local fallback only. To
+re-enable temporarily:
+
+```bash
+cp infra/systemd/archived/custodian-sync.* ~/.config/systemd/user/
+systemctl --user daemon-reload
+systemctl --user enable --now custodian-sync.timer
+```