The C5 probe failed for the wrong reason: plex.container lost its Network=
key in the same edit churn that ate tautulli's ContainerName. Plex ran on
the default podman network — published 32400 still worked (clients fine)
but tautulli could not resolve the plex alias, breaking the seeded
PMS_Web_Host=plex. Restore appnet membership; structure now parallel to
tautulli.container. Lesson recorded: after multi-hunk line edits on these
unit files, diff the whole file — key-order churn has eaten three keys
already.