Agent Plugin Package Fixture

This is the clean external Agent Plugins 1.0 package used by the UZE store and integration conformance tests. It contains only plugin.json and skills/; it deliberately has no .agents, .claude, .codex, or other harness configuration.

The UZE E2E installs this package once into a temporary $UZE_HOME, reads its SKILL.md as a package resource (engine::package_resources), and passes the same stored resource identity to peer integrations. The proof token is behavioral evidence that the skill was exposed and followed; it is not a cryptographic proof. Native discovery fixtures are deliberately separate.