fix: count Codex user_message turns in _count_human_messages (#347)

The _count_human_messages() function previously only handled Claude Code
transcript format: {"message": {"role": "user", "content": "..."}}

Codex CLI transcripts use a different schema:
{"type": "event_msg", "payload": {"type": "user_message", "message": "..."}}

This meant the stop-hook auto-save threshold never triggered for Codex
sessions because the count always returned 0.

Added detection for the Codex format so both Claude Code and Codex CLI
transcripts are counted correctly.

mempalace/hooks_cli.py

@@ -63,6 +63,14 @@ def _count_human_messages(transcript_path: str) -> int:
                             if "<command-message>" in text:
                                 continue
                         count += 1
+                    # Also handle Codex CLI transcript format
+                    # {"type": "event_msg", "payload": {"type": "user_message", "message": "..."}}
+                    elif entry.get("type") == "event_msg":
+                        payload = entry.get("payload", {})
+                        if isinstance(payload, dict) and payload.get("type") == "user_message":
+                            msg_text = payload.get("message", "")
+                            if isinstance(msg_text, str) and "<command-message>" not in msg_text:
+                                count += 1
                 except (json.JSONDecodeError, AttributeError):
                     pass
     except OSError: