feat(relocate): receive cloudinit and railiance-plan-host from railiance-cluster

Per ADR-003: cloud-init (S1 node provisioning) and host planning tool
belong at the Infrastructure Substrate layer. Moved from railiance-cluster.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cloudinit/user-data.yaml

@@ -0,0 +1,12 @@
+#cloud-config
+package_update: true
+package_upgrade: true
+users:
+  - name: ubuntu
+    sudo: ALL=(ALL) NOPASSWD:ALL
+    groups: sudo
+    shell: /bin/bash
+    ssh_authorized_keys:
+      - ssh-ed25519 AAAA...replace_with_your_pubkey
+runcmd:
+  - [ sh, -lc, 'echo Railiance seed host initialized' ]