emitPathOption function
Like emitOption, but absolutized — so the baked-in service command finds the file regardless of the service's working directory.
Only for filesystem paths. --node-path and --shell-path look like
paths but are HTTP mount points: absolutizing them would bake
--node-path /home/you/omnyserver/node into the unit and the Hub would
serve nodes on a nonsense route.
Implementation
void emitPathOption(List<String> out, String name, Object? value) {
if (value == null) return;
final s = value.toString();
if (s.isEmpty) return;
out
..add('--$name')
..add(p.normalize(p.absolute(s)));
}