fix: emit current Codex hook and skills formats

[RahulRaj97]

Summary

Fix the Codex adapter to emit the current Codex config shapes for both hook overlays and subagent skills config.

This addresses the Codex startup warnings caused by stale AgentMesh-generated output:

• was emitted with top-level instead of
• used a legacy string instead of structured skills config

Changes

• write Codex hooks under
• update Codex hook removal and empty-file checks to use the current schema
• normalize imported Codex subagent skills from into AgentMesh canonical list form
• emit Codex subagent skills back out as structured config
• update adapter tests and CLI flow fixtures to match the current Codex schema

Why

Recent Codex versions reject the old generated shapes, which leads to warnings like:

• malformed agent role definition
• failed to parse hooks config

The adapter should emit only the current Codex schema so users can delete stale output and regenerate clean runtime files with AgentMesh.