MetaCrate/AGENTS.md

All code and API mappings must be cross-platform; do not use macOS-only APIs unless equivalent Linux and Windows implementations are provided. Gitea Actions workflows must target only ubuntu-latest; do not add macOS or Windows Gitea jobs. Crates named libremetaverse-* are restricted to compatibility mappings of the C# LibreMetaverse libraries. New MetaCrate-native functionality must use a metacrate-* crate name; the reusable wgpu renderer is metacrate-rendering-wgpu.