feat: add hermes backend support

- Add myhermes entrypoint and myagents hermes subcommand
- Hermes sessions read from global SQLite store (~/.hermes/state.db)
- Default args: --yolo
- Update README, AGENTS.md, Makefile, pyproject.toml
- Add tests for hermes subcommand, passthrough, and session listing

AGENTS.md

@@ -45,7 +45,7 @@ myagents/
 ├── myagents/           # Python 源码
 │   ├── cli.py          # CLI entrypoint
 │   ├── launcher.py     # Agent 启动器
-│   ├── entrypoints.py  # myclaude / mykimi 独立入口
+│   ├── entrypoints.py  # myclaude / mykimi / mycodex / myhermes 独立入口
 │   ├── commands/       # 子命令
 │   └── ...
 ├── templates/          # 模板目录