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

AGENTS.md

@@ -4,6 +4,11 @@
 
 **Purpose:** Standalone State Hub service repository extracted from the-custodian/state-hub. Owns the FastAPI API, MCP server, dashboard, migrations, consistency tooling, and operational docs.
 
+**Periodic consistency sync:** The 15-minute workplan↔DB sweep is scheduled on
+activity-core (Railiance01), not a local timer. Execution still runs on this
+workstation via the bridge tunnel. Runbook:
+[`docs/consistency-sweep-runbook.md`](docs/consistency-sweep-runbook.md).
+
 **Domain:** custodian
 **Repo slug:** state-hub
 **Topic ID:** `cee7bedf-2b48-46ef-8601-006474f2ad7a`