- Add plugin_loader_v2.rs with nyash.toml v2 support
- Create PluginBoxV2 as temporary wrapper for v2 plugins
- Update runner.rs to use v2 loader instead of legacy BID registry
- Update box_registry.rs to work with v2 plugin system
- Support single FFI entry point (nyash_plugin_invoke) + optional init
- Integrate with existing BoxFactoryRegistry for seamless Box creation
- All compilation errors resolved, ready for testing
