Cut the comment bloat from the Podman playbooks

Comment blocks now stay within three lines and explain only the non-obvious. Long histories, include examples, and commented-out code are gone. No task, key, or value changed; the only data change is comment text inside the generated unit files.

postgres/playbook.yml

@@ -1,25 +1,5 @@
 ---
-# Deploys PostgreSQL as a rootless Podman Quadlet unit.
-#
-# Connects as the container user and runs everything as that user: the Quadlet
-# units belong to it, so the connection's PAM session is what makes
-# `systemctl --user` work without any environment juggling.
-#
-# gather_facts is required: podman_user and the home directory come from the
-# user_id / user_dir facts.
-#
-# The rootless-Podman prerequisites (installing podman, enabling lingering, the
-# low-port sysctl, creating the Quadlet directory) are deliberately NOT applied
-# here. They are the shared task file at caddy/roles/podman/tasks/main.yaml, and
-# a host that has already run caddy/playbook.yml has them:
-#
-#   - name: Rootless Podman prerequisites
-#     ansible.builtin.include_tasks: "{{ playbook_dir }}/../caddy/roles/podman/tasks/main.yaml"
-#
-# The variables those tasks need are duplicated at the top of vars/default.yml,
-# so this play stands on its own.
-#
-# Run with: ansible-playbook -u tanshu postgres/playbook.yml
+# Run this before the app playbooks. Each service attaches itself.
 - name: Deploy PostgreSQL as a rootless Podman Quadlet
   hosts: emily
   gather_facts: true
@@ -27,6 +7,4 @@
     - vars/default.yml
 
   roles:
-    # The base postgres unit. It does NOT know which app networks it serves.
-    # Each service attaches itself via postgres/roles/attach.
     - postgres