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-resume/scripts/update_yaml_resumed.sh

@@ -4,17 +4,17 @@
 # resume UUID 를 per-row own id (claude_session_id_own / agy_conversation_id_own)
 # 에 박는다 — agent_identities 전역은 더 이상 primary 아님 (cache 로 강등, P0-C/단계 e).
 #
-# Usage: bash update_yaml_resumed.sh --session <name> --uuid <id> [--agent claude|agy|hermes|grok|opencode]
+# Usage: bash update_yaml_resumed.sh --session <name> --uuid <id> [--agent claude|agy|hermes|grok|opencode|codex]
 set -euo pipefail
 
 source "$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)/lib.sh"
 
 usage() {
   cat <<EOF
-Usage: $0 --session <name> --uuid <id> [--agent claude|agy|hermes|grok|opencode] [--herdr-session <name>] [--cmd-full <cmd>]
+Usage: $0 --session <name> --uuid <id> [--agent claude|agy|hermes|grok|opencode|codex] [--herdr-session <name>] [--cmd-full <cmd>]
 
 --uuid may be empty for an Issue-3 Class A fresh-spawn resume (agy/hermes/
-opencode 0-turn stopped session, no conversation id ever assigned) - pass
+opencode/codex 0-turn stopped session, no conversation id ever assigned) - pass
 --cmd-full so the display command can be recorded without a uuid to embed.
 EOF
 }
@@ -235,6 +235,16 @@ elif agent == 'opencode':
     cp = os.environ.get('CHILD_PID', '0')
     if cp.isdigit() and int(cp) > 0:
         target['child_pid'] = int(cp)
+elif agent == 'codex':
+    target['pane']['cmd'] = 'codex'
+    if uuid:
+        target['pane']['cmd_full'] = f'codex resume --dangerously-bypass-approvals-and-sandbox {uuid}'
+        target['codex_session_id_own'] = uuid
+    else:
+        target['pane']['cmd_full'] = os.environ.get('CMD_FULL_OPT', '') or 'codex --dangerously-bypass-approvals-and-sandbox'
+    cp = os.environ.get('CHILD_PID', '0')
+    if cp.isdigit() and int(cp) > 0:
+        target['child_pid'] = int(cp)
 
 snap = d.setdefault('snapshot', {})
 snap['taken_at'] = now