Add Codex compatibility

[huichalaf]

Summary

• Add OpenAI Codex plugin packaging, local marketplace metadata, and runtime-aware workspace/manifest/skill path resolution.
• Add a Codex-safe MCP launcher and Codex workspace template.
• Add a registry-backed Codex runner for reminders, heartbeat, and dreaming, plus launchd/systemd service planning that runs the runner with codex exec.
• Make channels_detect useful under Codex by reporting native WebChat, webhook, and voice surfaces while keeping Claude channel plugins and Claude launch flags clearly marked as Claude-only.
• Update docs, skills, and tests so Codex instructions use the Codex adapters instead of Claude Code-only APIs.

Validation

• npm test
• node --check bin/clawcode-codex-cron-runner.mjs
• git diff --check
• Local Codex plugin install in a temporary Codex home: codex plugin marketplace add, codex plugin add, and codex plugin list
• MCP smoke under CLAWCODE_RUNTIME=codex: verified channels_detect and service_plan return Codex responses without errors
• Runner smoke with a fake codex binary: an expired one-shot reminder executes first, then tombstones successfully
• Privacy scan of the full PR diff for personal/company emails, local user paths, and common secret token patterns: no matches

Notes

Claude Code APIs such as native CronCreate/CronList/CronDelete, Claude channel launch flags, claude --continue, and Claude channel plugin envelopes remain Claude-specific. Under Codex, ClawCode now uses Codex-native adapters instead: the registry runner for reminders/dreaming and the HTTP bridge for WebChat/webhooks.