chore: drop dead templates/workspace and stale doc references

Nothing in the codebase ever read templates/workspace/; workspace
bootstrap is handled by the xiaohe runtime sync (MANAGED_PATHS).
README/AGENTS.md structure trees and the first-run claim updated.

AGENTS.md

@@ -48,8 +48,6 @@ myagents/
 │   ├── entrypoints.py  # myclaude / mykimi / mycodex / myhermes 独立入口
 │   ├── commands/       # 子命令
 │   └── ...
-├── templates/          # 模板目录
-│   └── workspace/      # workspace 模板 (AGENTS.md, CLAUDE.md symlink, .gitignore)
 └── .agents/            # Agent 运行时配置（含向后兼容的 .claude 软链接）
 
 workspace/              # 主工作环境 (默认 --cwd 目标, 独立目录)