fix(test): 修 watcher 测试在 macOS 上空转

`test:capabilities` 在 macOS 上一直是红的,挡住 #1 / #2 / #5 三个 PR 的合并。
根因是路径的两种拼法:

- 测试的期望值来自 `mkdtemp(join(tmpdir(), ...))`,在 macOS 上是未解析的
  `/var/folders/...`
- `createWorkspaceGitWatcher` 内部做了 `realpath`,返回 `/private/var/folders/...`

而 `/var` 是 `/private/var` 的符号链接。

**实现是对的** —— 文件系统 watcher 必须用真实路径,用符号链接那种拼法不保证
指向同一个 inode。错的是测试拿未解析的路径去比。

## 这个测试此前没有在验任何东西

`mkdtemp` 的返回值用在两处。断言 `directory === workspace` 因此永远不成立;
更要紧的是闭包里

    if (directory === workspace) watchWorkspacePath = listener;

也永远不成立,于是 `watchWorkspacePath` 保持 `undefined`,紧接着的
`watchWorkspacePath?.('.git/index')` 变成一次空调用 —— 后面
`expect(onChange).toHaveBeenCalledWith('repository')` 验的是一个从未被触发的
监听器。

所以它不是「因为路径 bug 而失败」,它是**什么都没验就绿了**,直到
`#4` 修好 `typecheck:test`、CI 终于跑到这个门,才把一直没生效的断言暴露出来。

## 验证

- `capability` 套件 5149 passed / 0 failed(此前 5148 + 1 failed)
- 反向验证:去掉 `realpath` 后该测试转红 —— 证明它现在真的在验

Author: probe

packages/local-runtime-v2/src/service/workspace/snapshot/watcher.test.ts

@@ -1,6 +1,6 @@
 import { EventEmitter } from 'node:events';
 import type { FSWatcher } from 'node:fs';
-import { mkdtemp, mkdir, rm } from 'node:fs/promises';
+import { mkdtemp, mkdir, realpath, rm } from 'node:fs/promises';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { afterEach, describe, expect, it, vi } from 'vitest';
@@ -47,8 +47,19 @@ describe('createWorkspaceGitWatcher', () => {
 });
 
 async function createWorkspace(): Promise<string> {
-  const workspace = await mkdtemp(join(tmpdir(), 'workspace-git-watcher-'));
-  temporaryDirectories.push(workspace);
+  const created = await mkdtemp(join(tmpdir(), 'workspace-git-watcher-'));
+  temporaryDirectories.push(created);
+  // macOS: `tmpdir()` is `/var/folders/...` and `/var` is a symlink to
+  // `/private/var`. `mkdtemp` hands back the UNRESOLVED path; the watcher
+  // realpaths before it watches, which is the correct behaviour — a filesystem
+  // watch on the symlink spelling is not reliably the same inode.
+  //
+  // Comparing the unresolved path against the resolved one is not only a
+  // failing assertion: the helper closure picks the listener with
+  // `directory === workspace`, so that comparison never matched, the listener
+  // stayed undefined, and the `?.()` call after it silently did nothing. The
+  // test was not failing because of a path bug. It was passing over nothing.
+  const workspace = await realpath(created);
   await mkdir(join(workspace, '.git', 'refs', 'heads'), { recursive: true });
   await mkdir(join(workspace, '.git', 'info'), { recursive: true });
   return workspace;