More group node input types

For procedural materials it would be nice to create and store function nodes for reuse in a library.

new Group Inputs needed:
- bool (checkbox) as Group Input value
- enums as Group Input value + switch / condition Node

The issue names no files, tests, or entry points. Start by locating the group-input and procedural-material node handling, then trace how boolean and enum values are represented and how switch or condition nodes are created. Done means reusable function nodes can be stored in a library and group inputs support checkboxes, enums, and the requested control flow.

Written by the indexing model from the issue text.