Add a root plugin.json manifest and move the skill to the canonical
skills/core-data-expert/ location per the Agent Plugins specification
(https://agent-plugins.org). A symlink at the old root path keeps
existing clones and scripts working until the next major version.
Also completes client wrapper coverage: new Cursor plugin manifest with
logo, pi package.json, and Codex agents/openai.yaml including ChatGPT
desktop interface metadata. Release workflow now bumps every manifest.
Antoine van der Lee