Add dockhand role to initial_install

Tagged never,dockhand_install so it only runs when explicitly requested.
Installs docker.io + docker-compose-v2, templates a compose file for
fnsys/dockhand:latest at /docker/dockhand, and wires a oneshot systemd
unit that brings the stack up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

initial_install/roles/dockhand/templates/docker-compose.yml.j2

@@ -0,0 +1,14 @@
+# Managed by Ansible — do not edit by hand.
+services:
+  dockhand:
+    image: fnsys/dockhand:latest
+    container_name: dockhand
+    restart: unless-stopped
+    ports:
+      - "3000:3000"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+      - dockhand_data:/app/data
+
+volumes:
+  dockhand_data: