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/lib_py/agents/registry.py

@@ -7,6 +7,7 @@ from lib_py.agents.adapters.agy import AgyAgentAdapter
 from lib_py.agents.adapters.hermes import HermesAgentAdapter
 from lib_py.agents.adapters.grok import GrokAgentAdapter
 from lib_py.agents.adapters.opencode import OpenCodeAgentAdapter
+from lib_py.agents.adapters.codex import CodexAgentAdapter
 
 _ADAPTERS: Dict[str, BaseAgentAdapter] = {
     'claude': ClaudeAgentAdapter(),
@@ -14,6 +15,7 @@ _ADAPTERS: Dict[str, BaseAgentAdapter] = {
     'hermes': HermesAgentAdapter(),
     'grok': GrokAgentAdapter(),
     'opencode': OpenCodeAgentAdapter(),
+    'codex': CodexAgentAdapter(),
 }
 
 def get_adapter(agent_name: str) -> Optional[BaseAgentAdapter]: