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.

nextcloud/roles/valkey/handlers/main.yaml

@@ -1,18 +1,6 @@
 ---
-# Valkey is its own playbook (valkey/playbook.yml) and a rootless Quadlet unit
-# there. This handler runs as the connection user, which is what makes
-# `systemctl --user` work here.
-#
-# Required by valkey/roles/attach, which notifies it whenever this app's drop-in
-# changes: a new drop-in changes the generated unit, so Valkey must be recreated
-# to join the network — Quadlet has no live equivalent of
-# `podman network connect`.
-#
-# Data survives the recreate: RDB persistence is on by default, the stop is
-# graceful, and the new container loads the snapshot back off the bind mount. What
-# does not survive is availability — for the seconds the container is down,
-# Nextcloud's PHP sessions and `memcache.locking` are unreachable. See
-# valkey/readme.md, "The trade-off".
+# A new drop-in changes the generated unit, so Valkey is recreated to join the network.
+# Data survives the recreate, but Nextcloud's cache and locks are unavailable for the seconds it is down.
 - name: Restart Valkey
   ansible.builtin.systemd_service:
     name: "{{ valkey_unit }}"

nextcloud/roles/valkey/tasks/main.yaml

@@ -1,28 +1,8 @@
 ---
-# Attach this app's network to the shared Valkey unit.
-#
-# Valkey knows nothing about its clients, exactly like Caddy and Postgres: a
-# service joins by dropping 50-nextcloud.conf and the shared
-# 10-network-aliases.conf next to valkey.container. The canonical way to do that
-# is the shared include below — it writes the same bytes every service writes,
-# asserts that nextcloud.network already exists, and notifies the "Restart
-# Valkey" handler defined in this role.
-#
-# `redis` is the alias the app connects to, not the container name: it is the host
-# an instance configured for Redis has in config.php. This playbook does not write
-# that configuration, it only makes the name resolvable.
-
+# The app connects to `redis`, the alias the attach role adds, not the container name.
 - name: Attach Nextcloud to Valkey
   ansible.builtin.include_tasks: "{{ playbook_dir }}/../valkey/roles/attach/tasks/main.yaml"
 
-# On a first attach the drop-in is new, so Valkey has to be recreated to join
-# nextcloud_net — and that restart is a *handler*, which by default runs at the
-# end of the play, after the nextcloud role has already started the app. The app
-# would then come up before `redis` resolves; with `memcache.locking` on Redis it
-# would fail on the first write rather than at startup, which is a worse failure
-# to debug.
-#
-# Flushing applies the new drop-in before the app starts. On later runs the
-# drop-in is unchanged, nothing is pending, and this is a no-op.
+# The restart that joins Valkey to nextcloud_net is a handler, so flush it before the app starts or it fails on the first cache write.
 - name: Apply the Valkey network change before starting Nextcloud
   ansible.builtin.meta: flush_handlers