Vendored Wargame Engine

This is a vendored copy of maximinus/wargame, kept in-repo so the RG40XXV prototype does not depend on installing Python packages onto KNULLI.

The first RG client uses a small pygame client with Wargame-style scene/node boundaries because upstream Wargame owns its loop and is sparse around modern Python packaging. The vendored package is still present for direct imports and later migration.

Local compatibility patches:

• yaml.load(...) changed to yaml.safe_load(...) for current PyYAML.
• board.py imports BaseNode from wargame.nodes; the upstream file referenced a missing wargame.node.

Upstream README and license are preserved as README-upstream.md and LICENSE.