An instance unique name Akka refuses as a path element (space, '#', '/',
non-ASCII) made Context.ActorOf throw on the singleton's own thread; the
default Restart stopped every Instance Actor on the site. DeployCompileValidator
now checks the instance + script/alarm/native-source actor names with
ActorPath.IsValidPathElement (the Commons ActorNameRules mirror is stricter
than Akka for " ( ), pinned by a parity sweep), CreateInstanceActor catches
InvalidActorNameException and every caller reports it, and the Instance Actor
skips a refused child name like a compile failure.