docs(book): chapter_1 补上工具安装与环境验证，与 README 三步对齐

chapter_1 是三份 README 的「更多细节」落点，但它的 §0 只装 xlings，
接着就直接 `d2x install d2mcpp` —— 一台干净的机器照着做会在第二条命令
上失败，因为 d2x 这个二进制根本还没装。

补两处，与 README 新的三步保持同一套说法：
- §0 结尾加 `xlings install d2x mcpp -y`，两个工具名链到各自仓库
- §1 加「验证环境」小节：`cd d2mcpp` + `mcpp test`，并说明「刚拿到课程
  时全部未通过」既是起点也是工具链已通的证据

Author: Sunrisepeak

book/en/src/base/chapter_1.md

@@ -32,6 +32,14 @@ wget https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_
 Invoke-Expression (Invoke-Webrequest 'https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_install.ps1' -UseBasicParsing).Content
 ```
 
+**With xlings in place, install the two tools this course needs**
+
+```bash
+xlings install d2x mcpp -y   # d2x: exercise framework CLI | mcpp: C++ build & test tool
+```
+
+> [d2x](https://github.com/d2learn/d2x) drives exercise checking and progression, [mcpp](https://github.com/mcpp-community/mcpp) builds and runs them — the exercises *are* mcpp tests
+
 ## 1. Get Project and Auto-configure Environment
 
 > Download the project to current directory and automatically configure local environment
@@ -40,6 +48,17 @@ Invoke-Expression (Invoke-Webrequest 'https://raw.githubusercontent.com/openxlin
 d2x install d2mcpp
 ```
 
+### Verify the environment
+
+> Run the full test suite once inside the project to confirm the toolchain works
+
+```bash
+cd d2mcpp
+mcpp test
+```
+
+> The exercises **are** the tests. On a fresh checkout this reports them all as failing — that is the expected starting point, and it already proves the compile-and-run path works. Drop the reference answers from `solutions/` in and the very same command goes all green.
+
 ### Local E-book
 
 > Execute `d2x book` command in the project directory to open local documentation (includes usage guide and e-book)

book/src/base/chapter_1.md

@@ -32,6 +32,14 @@ wget https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_
 Invoke-Expression (Invoke-Webrequest 'https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_install.ps1' -UseBasicParsing).Content
 ```
 
+**装好 xlings 后, 用它装本教程需要的两个工具**
+
+```bash
+xlings install d2x mcpp -y   # d2x: 练习框架 CLI | mcpp: C++ 构建与测试工具
+```
+
+> [d2x](https://github.com/d2learn/d2x) 负责练习的检测与推进, [mcpp](https://github.com/mcpp-community/mcpp) 负责构建与运行 —— 练习本身就是 mcpp 的测试
+
 ## 1.获取项目及自动配置环境
 
 > 下载项目到当前目录并自动配置本地环境
@@ -40,6 +48,17 @@ Invoke-Expression (Invoke-Webrequest 'https://raw.githubusercontent.com/openxlin
 d2x install d2mcpp
 ```
 
+### 验证环境
+
+> 进入项目目录后跑一遍全量测试, 确认工具链是通的
+
+```bash
+cd d2mcpp
+mcpp test
+```
+
+> 练习**就是**测试。刚拿到课程时这里会报告全部未通过 —— 这正是练习的起点, 同时也说明编译运行这条链路已经跑通了。把 `solutions/` 里的参考答案覆盖进去, 同一条命令就会全绿。
+
 ### 本地电子书
 
 > 可以在项目目录执行`d2x book`命令, 打开本地文档(包含使用说明和电子书)