Reverts the explicit subnets: the pools were freed by deleting five networks, so
the network role is back to its single idempotent task - ensure the network
exists and Caddy is on it - and the Sites no longer declare a subnet. The
deployment readme keeps the note that a new Site needs a config, and therefore a
new tag, but no longer asks for a free /24.
If the pools fill up again the failure is recognisable: 'all predefined address
pools have been fully subnetted', and the choices are deleting stale networks or
declaring a subnet per Site.
tanshu
2ef044aa45