Add the menu-admin playbook

Deploys the menu app for one Site: pulls the tag, creates the data root, runs
the container against a config baked into the image, waits for health, verifies
the data directory, and points Caddy at the app with a marker it can update in
place. The parallel run uses a temporary hostname; cutover sets the retire
flags.

menu-admin/playbook.yml

@@ -0,0 +1,19 @@
+---
+# Deploys the menu app for one Site. Copy this directory to
+# ansible-playbooks/menu-admin/ and run it from there:
+#
+#   ansible-playbook -l monoco -e site=hopsngrains -e tag=<tag> playbook.yml
+#
+# The first run targets a temporary vhost (menu-new...) so the new site can be
+# checked against the live one. Cutover is the same playbook with the real vhost
+# and the two retire flags set; see readme.md.
+- hosts: all
+  become: true
+  vars_files:
+    - vars/default.yml
+    - "vars/{{ site }}.yml"
+
+  roles:
+    - network
+    - menu-app
+    - caddy