refactor: Move recipe generator to cook/ directory and fix flattening bugs

- Move recipe-generator/ to cook/ for cleaner structure

- Fix ksflatten-relative path conversion to handle all %include paths

- Fix validation exit code to only fail on actual errors

- All recipes now generate and flatten successfully via make all

cook/bin/generate-recipe

@@ -0,0 +1,2 @@
+#!/bin/bash
+exec "$(dirname "$0")/../recipe-generator/generate_recipe.py" "$@"