feat(legacy-meter): schedule 8h capture activity on railiance01

Add legacy-meter-8h-capture cron (0 */8 * * * UTC), pass hours through the
state-hub resolver, and label progress summaries by window size.

k8s/railiance/20-runtime.yaml

@@ -328,6 +328,41 @@ data:
     Railiance projection of the Custodian-owned definition in
     `activity-definitions/weekly-legacy-meter-review.md`. Posts
     `legacy_meter_weekly_review` progress for STATE-WP-0069 retirement gating.
+  legacy-meter-8h-capture.md: |
+    ---
+    id: legacy-meter-8h-capture
+    name: Legacy-Meter 8h Capture
+    type: activity-definition
+    version: "1.0"
+    enabled: true
+    owner: custodian
+    governance: custodian
+    status: active
+    created: "2026-07-09"
+    trigger:
+      type: cron
+      cron_expression: "0 */8 * * *"
+      timezone: UTC
+      misfire_policy: skip
+    context_sources:
+      - type: state-hub
+        query: legacy_meter_weekly_review
+        required: true
+        params:
+          hours: 8
+          evidence_sinks:
+            - type: state-hub-progress
+              event_type: legacy_meter_8h_capture
+              author: activity-core
+              workplan_id: 44e2e123-9934-4b5e-8b50-1bac548c5b70
+        bind_to: context.legacy_meter_weekly_review
+    ---
+
+    # ActivityDefinition: Legacy-Meter 8h Capture
+
+    Railiance projection of the Custodian-owned definition in
+    `activity-definitions/legacy-meter-8h-capture.md`. Posts
+    `legacy_meter_8h_capture` progress every 8h for STATE-WP-0073 retirement gating.
   phase5-stabilization-closeout.md: |
     ---
     id: "e7d2b5a8-4c1f-4e9a-b6d3-8f2a1c4e6b09"