Fix WMO MOHD chunk parsing by adding missing nTextures field

The MOHD header structure was missing the nTextures field at the start,
causing all subsequent field reads to be offset by 4 bytes. This corrupted
bounding box values and caused floor geometry to be incorrectly culled.

include/pipeline/wmo_loader.hpp

@@ -149,8 +149,9 @@ struct WMOGroup {
 
 // Complete WMO Model
 struct WMOModel {
-    // Root WMO data
+    // Root WMO data (from MOHD chunk)
     uint32_t version;
+    uint32_t nTextures;  // Added - was missing, caused offset issues
     uint32_t nGroups;
     uint32_t nPortals;
     uint32_t nLights;