Let the catalog describe clothes and carryables on ThingDef without dressing anyone.

Empty layers keep furniture on the map; a known layer set and ColorDef palette reject unknown ids at load.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/HSchool.Server/Api/ModEndpoints.cs

@@ -167,7 +167,7 @@ internal sealed record CatalogResponse(
 
     private static IReadOnlyList<DefInfoResponse> PlaceableThings(DefCatalog catalog, string locale) =>
         catalog.Things.Values
-            .Where(def => !def.Abstract)
+            .Where(def => !def.Abstract && def.Layers.Count == 0 && !def.Portable)
             .OrderBy(def => def.DefName, StringComparer.Ordinal)
             .Select(def => new DefInfoResponse(def.DefName, catalog.Label(locale, def), def.PupilSlots))
             .ToArray();