Retire the readline front door and the repl-agent example

Delete packages/ui/stdio and examples/repl-agent; rename stdio-demo to
@deepseek-ai/dsh-tui-demo (TUI-only, refuses pipes before Loader boot).
tui-agent owns the coding composition inline; echo-agent and the CI demo
smoke move to the one-shot cli-demo bin, which gains -p/--prompt. The
UI-independent with-key e2es move verbatim to tui-agent. SDK wizard's
'stdio' interface becomes 'tui'. PTY testing stays confined to TUI
surfaces; all other subprocess tests ride pipes.

See .agents/notes/implemented/simplification/2026-07-20-retire-readline-front-door.md

README.zh.md

@@ -4,6 +4,16 @@
 
 **DeepSeek Harness SDK** 是用于构建 agent harness（智能体框架）的 SDK，采取基于插件的设计。
 
+## 安装
+
+一行命令即可安装 `dsh` 编码智能体——需要 `git` 和 Node `^22.19 || >=24`，缺少 `pnpm` 时会询问是否代为安装：
+
+```sh
+curl -fsSL https://raw.githubusercontent.com/deepseek-harness/deepseek-harness/master/scripts/install.sh | sh
+```
+
+脚本会把 harness 克隆到 `~/.dsh/source`，运行 `pnpm install`，把 `dsh` 软链接到 `~/.local/bin`（并询问是否加入 PATH），提示输入一次 `DEEPSEEK_API_KEY`，随后启动 `dsh`；再次运行会更新已有的检出。若在检出目录内运行（`sh scripts/install.sh`），脚本会复用当前检出并跳过克隆。可覆盖的 `DSH_*` 变量见 [`scripts/install.sh`](scripts/install.sh)。
+
 ## 开发
 
 本 monorepo 基于 [Cordis](https://github.com/cordiverse/cordis) 框架构建（以源码形式收录在 `vendor/` 下），采用微内核风格：所有功能都以插件形式提供。