Verify skills load in Codex CLI, check native plugin format

[sgraczyk]

Problem

The table claims Codex CLI reads ~/.agents/skills. No check proves it. It is unknown if Codex has a native plugin format.

Change

Install skills in Codex CLI. Confirm the commands load. Check Codex docs for a native plugin format. Package only if the format exists.

Accept

• Skills load in Codex CLI, or the fault is filed.
• Native format exists or it does not. Record the result.
• supported-hosts.md reflects the result.