feat(agent): add full codex agent support (v4.2.0)

- Implement CodexAdapter in lib_py/agents/adapters/codex.py with safe flags and TUI readiness
- Extend create_session, resume_session, stop_session, and reconcile for codex CLI
- Support codex agent delegation and loop integration across all multi-agent skills
- Add unit, component, and contract test suites for codex integration
- Verify all 462 tests passing cleanly

.agents/skills/multi-agent-mux-status/SKILL.md

@@ -1,14 +1,14 @@
 ---
 name: multi-agent-mux-status
 description: "Read-only instant snapshot of all agent herdr sessions — name, YAML status, herdr alive, pane cmd/cwd, resume UUID on disk, and any drift. No mutation. Reuses reconcile.sh --dry-run for the diff logic. Use when you want to know 'what's running RIGHT NOW' without spinning up the monitor loop."
-version: 4.1.3
+version: 4.2.0
 author: godopu
 license: MIT
 platforms: [linux, macos]
 environments: [terminal, herdr]
 metadata:
   hermes:
-    tags: [agent, herdr, claude, antigravity, agy, grok, status, read-only, snapshot]
+    tags: [agent, herdr, claude, antigravity, agy, grok, opencode, codex, status, read-only, snapshot]
     related_skills: [multi-agent-mux-create, multi-agent-mux-resume, multi-agent-mux-stop, multi-agent-mux-monitor]
     prereq_skills: [multi-agent-mux-create, multi-agent-mux-monitor]
 ---