Mirrors the editor-side ZoneManifest sanitize on the discovery
scanner used by the launcher and asset manager. A custom_zones/
zone with bad mapId or out-of-range tile coords would otherwise
appear in the picker and silently fail when the user selects it.
- CustomZoneDiscovery scans directories for zone.json manifest files
- Discovers custom zones in custom_zones/ and output/ directories
- Reports: name, author, description, creature/quest availability
- Client can list all available custom expansions at startup
- Foundation for a zone selection menu in the client UI