Fix geoset filtering using correct geosetId from M2 batch

M2 batches have a geosetIndex field that determines the geoset group for
filtering (0-18=body, 1xx=hair, etc.). We were incorrectly using submeshId
from the submesh struct instead. Now properly stores and uses geosetId.

src/pipeline/m2_loader.cpp

@@ -627,6 +627,7 @@ bool M2Loader::loadSkin(const std::vector<uint8_t>& skinData, M2Model& model) {
             batch.textureUnit = db.textureCoordIndex;
             batch.transparencyIndex = db.textureWeightIndex;
             batch.textureAnimIndex = db.textureTransformIndex;
+            batch.geosetId = db.geosetIndex;  // Geoset ID for filtering (from batch, not submesh)
 
             // Look up proper vertex/index ranges from submesh
             if (db.skinSectionIndex < submeshes.size()) {