Schedule Core Hub stabilization checks for T02 sign-off

Add daily and closeout ActivityDefinitions, a manual stabilization script,
runbook, and workplan notes for the 2026-07-03 to 2026-07-10 window.

activity-definitions/core-hub-stabilization-closeout.md

@@ -0,0 +1,47 @@
+---
+id: "c5d9f3a2-7b4e-5f6c-0a1d-3e8f9b2c4d5e"
+name: "Core Hub Stabilization Closeout Check"
+type: activity-definition
+version: "1.0"
+enabled: true
+owner: core-hub
+governance: core-hub
+status: active
+created: "2026-07-07"
+trigger:
+  type: scheduled
+  at: "2026-07-10T17:35:00+00:00"
+  timezone: UTC
+context_sources:
+  - type: core-hub
+    query: stabilization_check
+    required: true
+    params:
+      source: activity-core
+      closeout: true
+      base_url: "https://hub.coulomb.social"
+      window_start: "2026-07-03T00:00:00+00:00"
+      window_end: "2026-07-10T17:35:00+00:00"
+      min_widget_types: 26
+      evidence_sinks:
+        - type: state-hub-progress
+          event_type: core_hub_stabilization_closeout
+          author: activity-core
+          workstream_id: a8d66822-e435-4b1e-ad81-37a298d1795e
+          task_id: 16eb7ce3-b574-4667-a189-c14ff5d0502b
+    bind_to: context.core_hub_stabilization_check
+---
+
+# ActivityDefinition: Core Hub Stabilization Closeout Check
+
+## Purpose
+
+One-shot closeout gate at the end of the Core Hub stabilization window. When
+`overall_pass` is true, the result sets `operator_signoff_needed=true` so the
+operator can approve `CORE-WP-0007-T02` (Inter-Hub rename / rollback retirement).
+
+## Output Contract
+
+- one State Hub progress event with `event_type: core_hub_stabilization_closeout`
+- fails the activity run when closeout checks do not pass
+- operator records the retirement decision separately in State Hub