Clarify Codex Claude scope and private skills

[hun99999]

Summary

• clarify that Codex and Claude Code are the current first-class public setup targets
• document that private project skills such as auto-eva stay in local runtime skill homes, not the public catalog
• add skill QA and ChatGPT artifact-exchange rules, including local/runtime validation expectations

Validation

• python3 -m unittest discover -s tests -p 'test_*.py'
• python3 scripts/check_private_paths.py --repo-root .
• python3 scripts/audit_agent_stack.py
• git diff --check
• quick_validate.py for local/runtime chatgpt-collaboration-harness and hun-engineering-loop
• quick_validate.py for local Codex/Claude auto-eva skill
• ChatGPT Pro smoke test returned status ok / Korean / accepted

Notes

• auto-eva skill files were installed locally under ~/.codex/skills and ~/.claude/skills only; they are intentionally not committed to this public repository.
• OpenCode remains optional/reference; opencode topic was removed from repository metadata.