docs(CUST-WP-0025-T17): add stabilization closeout gate details

Document the automated post-cutover stabilization window, scheduled
activity-core jobs, probe contract, railiance01 deploy evidence, and
operator sign-off coupling to CORE-WP-0007-T02.

workplans/CUST-WP-0025-fos-hub-bootstrap.md

@@ -550,6 +550,60 @@ on `hub.coulomb.social`, and supersede decisions recorded for `CUST-WP-0047-T05`
 and `CUST-WP-0049-T06`. Inter-Hub remains rollback-only through
 `CORE-WP-0007` stabilization sign-off.
 
+### Stabilization closeout gate (2026-07-07 → 2026-07-10)
+
+Automated post-cutover stabilization for `CORE-WP-0007-T02` operator sign-off
+is live. Runbook: `/home/worsch/core-hub/docs/deployment/stabilization-signoff.md`.
+Progress events bind to workstream `a8d66822-e435-4b1e-ad81-37a298d1795e` /
+task `16eb7ce3-b574-4667-a189-c14ff5d0502b` (`CORE-WP-0007-T02`).
+
+| Item | Value |
+| --- | --- |
+| Window start | 2026-07-03 (production cutover) |
+| Window end | 2026-07-10T17:35:00Z (closeout job) |
+| Daily check | 09:00 Europe/Berlin via activity-core |
+| Closeout | one-shot at window end |
+
+**Automated checks** (`core-hub` context resolver `stabilization_check`):
+
+| Probe | Expected |
+| --- | --- |
+| `GET /healthz` | 200 |
+| `GET /readyz` | 200 |
+| `GET /api/v2/widget-types` | 200, count ≥ 26 |
+| `GET /api/v2/hubs` (unauthenticated) | 401 |
+
+Closeout sets `operator_signoff_needed=true` when `overall_pass=true`. Operator
+sign-off criteria: daily/closeout pass through the window, no rollback invoked
+since cutover, and explicit approval to retire the Inter-Hub k8s rollback
+deployment.
+
+**Scheduled jobs** (canonical ActivityDefinitions in `core-hub`):
+
+| Job | ActivityDefinition id | State Hub `event_type` |
+| --- | --- | --- |
+| Daily | `b4c8e2f1-6a3d-4e5b-9f0c-2d7e8a1b3c4d` | `core_hub_stabilization_check` |
+| Closeout | `c5d9f3a2-7b4e-5f6c-0a1d-3e8f9b2c4d5e` | `core_hub_stabilization_closeout` |
+
+Projected into `activity-core/k8s/railiance/20-runtime.yaml`. Manual companion:
+`make stabilization-check` in `core-hub` (`scripts/core_hub_stabilization_check.sh`).
+
+**activity-core on railiance01** (deployed 2026-07-07):
+
+- Image `activity-core:railiance01-prod` rebuilt/imported; `actcore-api`,
+  `actcore-worker`, `actcore-event-router` rolled out; `actcore-sync` registered
+  both schedules on Temporal.
+- Evidence sink fix (`activity-core` `726da05`): `core-hub` sources now post
+  State Hub progress.
+- First live event (cluster State Hub
+  `http://state-hub.state-hub.svc.cluster.local:8000`, 2026-07-07T22:43:55Z):
+  `Core Hub stabilization daily: pass; widget_types=26/26`.
+
+Note: activity-core posts to the **cluster** State Hub on railiance01, not the
+workstation fallback at `127.0.0.1:8000`. T17 coupling is closed; Haskell
+retirement (`CORE-WP-0007-T02`–`T04`) unblocks only after closeout pass and
+operator approval recorded in State Hub.
+
 ### T18 — Core Hub operator UI first screens
 
 ```task