M14: add n8n execution health telemetry

PROJECT_STATE.md

@@ -2329,3 +2329,30 @@ evidence yet."
   **210 passed, 1 warning**.
 - Exact next action: add authenticated n8n workflow heartbeats and execution results,
   surface stale/healthy workflow state, then update generated contracts and E2E coverage.
+
+## n8n execution health telemetry (2026-08-10)
+
+- Added an authenticated, canonical-workflow-only, idempotent heartbeat contract. Status
+  now records each workflow's last execution ID/result and classifies it as healthy,
+  stale, failed or without evidence. Scheduled scan evidence expires after 2h30 and the
+  daily RAGcore sync after 30h; event-driven workflows are not falsely marked stale just
+  because no business event arrived.
+- Registered target-workflow failures override older success evidence until a newer
+  successful execution arrives. The Automation UI renders these explicit states and
+  execution IDs instead of treating any historical timestamp as permanently healthy.
+- All four versioned n8n definitions now report a successful execution heartbeat with
+  bounded retries; the central error handler continues to register failed target runs.
+- Evidence: JSON validation for all four definitions, frontend lint, ruff and mypy passed;
+  focused integration tests **26 passed** and full Unraid suite **212 passed, 1 warning**.
+- Live deployment: API/web deployed at `c9a8609`; all five pre-existing n8n workflows
+  were exported to the recoverable appdata backup
+  `backups/mobilityops-pre-heartbeat-20260810.json` before the four definitions were
+  imported and published. The import initially exposed n8n CLI's unsafe name-only
+  credential resolution (both Header Auth nodes resolved to the service credential);
+  credential IDs were restored from the backup before republishing. A real return then
+  completed through outbox → server n8n → callback → heartbeat as execution `337`;
+  its first 403 delivery remained safely retryable and succeeded after the credential
+  correction. Live n8n state is operational and Vehicle Return is `healthy` with its
+  execution ID visible.
+- Exact next action: regenerate the checked-in OpenAPI contract, add E2E coverage for the
+  new operator workflows, document credential-safe n8n upgrades and run acceptance.