refactor(editor): extract zone lifecycle handlers into cli_zone_mgmt.cpp

Moves the four zone-level lifecycle handlers (--copy-zone,
--rename-zone, --remove-zone, --clear-zone-content) out of
main.cpp into a new cli_zone_mgmt.{hpp,cpp} module. All slug-
aware: copy + rename keep file names and manifest mapName in
sync so the result is self-consistent; clear-content empties
the per-feature JSONs without touching terrain.

main.cpp shrinks by 321 lines (4,431 to 4,110).

tools/editor/cli_zone_mgmt.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+namespace wowee {
+namespace editor {
+namespace cli {
+
+// Dispatch the zone-level lifecycle handlers — copy, rename,
+// remove, and clear-content operations on whole zone
+// directories. All slug-aware (file rename and manifest
+// mapName stay in sync) so the result is self-consistent.
+//   --copy-zone           duplicate a zone with a fresh slug
+//   --rename-zone         change a zone's slug + rename files
+//   --remove-zone         delete a zone directory (with confirmation)
+//   --clear-zone-content  empty creatures/objects/quests/items
+//
+// Returns true if matched; outRc holds the exit code.
+bool handleZoneMgmt(int& i, int argc, char** argv, int& outRc);
+
+} // namespace cli
+} // namespace editor
+} // namespace wowee