feat(zone): checking, keeping and locking a zone's edited files

Three pieces that know nothing of how a set of files arrives:
- ZonePublish reads every file of a set with the server's own readers and says, file
  by file, what is wrong; a set is good only when every file is.
- ZoneOverrideStore keeps a good set in the override folder: built in a staging
  folder, flushed, swapped in with a rename, the set before it kept as a backup.
  Restoring a backup and clearing a zone's set are the same swap.
- ZoneEditLock has the rules for a zone's editors and its one lock holder, and for
  holding a reload while players are in the zone.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

dCommon/ZoneFile.cpp

@@ -72,6 +72,7 @@ void ZoneFile::Read(std::istream& file) {
 		if (!ReadPaths(pathChunk)) {
 			LOG("The zone file's paths are not ones the client reads; the zone has no paths, as in the client");
 			paths.clear();
+			pathsRefused = true;
 		}
 	}
 }