seed: planned Scaleway backup store for WP-0002

Identity, topology, consumer bindings, and the planned attribute file
(region nl-ams, endpoint/bucket still null). Post-purchase fill is
REEF-STORAGE-WP-0002.

substrate/topology.yaml

@@ -0,0 +1,21 @@
+reef_id: reef-storage
+membership_policy: Add a member when a purchased object-store (bucket/project) is live. Members are provider resources, not hosts.
+members: []
+intended_members:
+  - member_id: platform-audit-storage
+    role: primary-backup-object-store
+    provider: Scaleway
+    product: standard-multi-az
+    region: nl-ams
+    resource_id: resource:platform:audit-storage
+    status: planned
+    evidence:
+      - repo: resource-control
+        path: docs/evidence/RESOURCE-WP-0002-primary-selection-2026-08-14.md
+access_surfaces:
+  - type: s3-https
+    note: Endpoint and bucket are filled after purchase in substrate/object-stores/platform-audit-storage.yaml. No rail.
+unresolved_questions:
+  - Scaleway project/organization id on the paying Railiance (or GmbH) account
+  - Exact bucket name and prefix after create
+  - Whether Host Europe Backup Storage or Nextcloud is the T06 second copy