fix: resolve enum issues with arrow marshalling

Author: Spelkington

examples/advanced/DroppedNeuralNet/.gitignore

@@ -5,9 +5,22 @@
 bin/
 obj/
 
-# Runtime data: historical dataset (large CSV — obtain from puzzle source)
-Data/_01_Raw/Datasets/historical_data.csv
-
-# Runtime outputs
-Data/_07_ModelOutput/solution.json
+# Generated metadata
 Metadata/
+
+# Ignore all generated data artifacts
+Data/**
+
+# Un-ignore layer directories and their Schemas subdirectories so git can traverse them
+!Data/*/
+!Data/*/Schemas/
+!Data/_01_Raw/Datasets/
+
+# Allow raw input dataset files
+!Data/_01_Raw/Datasets/*
+
+# Allow all schema and catalog .cs files
+!Data/**/*.cs
+
+# Un-ignore all .gitkeep files anywhere
+!**/.gitkeep