Fix case-sensitivity bug in TreeEnsembleModelParameters property access

The property `verNumFeaturesSerialized` was accessed with a lowercase 'v',
but all subclasses define the getter as `VerNumFeaturesSerialized` (uppercase 'V').
This caused `NumFeatures` to never be read from the binary data since the
comparison `context.modelVersionWritten >= undefined` always evaluates to false.

https://claude.ai/code/session_01LtcvK8Cj7hRt164unWGAmH

source/mlnet.js

@@ -1903,7 +1903,7 @@ mlnet.TreeEnsembleModelParameters = class extends mlnet.ModelParametersBase {
         const categoricalSplits = context.modelVersionWritten >= this.VerCategoricalSplitSerialized;
         this.TrainedEnsemble = new mlnet.InternalTreeEnsemble(context, usingDefaultValues, categoricalSplits);
         this.InnerOptions = context.string(null);
-        if (context.modelVersionWritten >= this.verNumFeaturesSerialized) {
+        if (context.modelVersionWritten >= this.VerNumFeaturesSerialized) {
             this.NumFeatures = reader.int32();
         }