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.

yamtrack/roles/valkey/handlers/main.yaml

@@ -1,16 +1,6 @@
 ---
-# Valkey is its own playbook (valkey/playbook.yml) and a rootless Quadlet unit
-# there. This handler runs as the connection user, so `systemctl --user` works
-# without setting XDG_RUNTIME_DIR.
-#
-# 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`.
-#
-# The cost is a cold cache for every attached app, not lost data — but note that
-# attached means every cache client, not just Yamtrack. See valkey/readme.md,
-# "The trade-off".
+# A new drop-in changes the generated unit, so Valkey must be recreated to join the network.
+# That restarts every attached client, not just Yamtrack.
 - name: Restart Valkey
   ansible.builtin.systemd_service:
     name: "{{ valkey_unit }}"