fix(git): 切换未跟踪文件显示模式以支持新文件夹内文件差异 (#242)

* fix(git): 切换未跟踪文件显示模式以支持新文件夹内文件差异
当使用 `git status --untracked-files=normal` 时，新文件夹会被折叠为单条 `?? dir/` 条目，点击后因无法读取目录（`fs.read` 报错 "is a directory"）而无法加载差异。切换至 `--untracked-files=all` 使新文件夹下的每个文件独立显示为一行，并可正常查看差异，与 VSCode 默认行为一致。同时添加回归测试以验证 porcelain 输出格式。

* test(git): 补真实 git 集成测试钉住 status() 的 --untracked-files=all（review feedback）

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Co-authored-by: Menghuan1918 <menghuan2003@outlook.com>

src/git.ts

@@ -143,13 +143,20 @@ export async function currentBranch(cwd: string): Promise<string> {
   return out.trim()
 }
 
-/** Working-tree status (untracked included). */
+/**
+ * Working-tree status (untracked included). `--untracked-files=all` lists
+ * the CONTENTS of new directories as individual entries (`?? newdir/a.ts`
+ * rather than a collapsed `?? newdir/`), so every row in the source-control
+ * panel is a real file whose diff tab can load. With `=normal`, git folds a
+ * new folder into one trailing-slash entry that has no diff output and
+ * cannot be read as a file.
+ */
 export async function status(cwd: string): Promise<GitStatusResult> {
   const repo = await isGitRepo(cwd)
   if (!repo) return { isRepo: false, entries: [] }
   const [branch, raw] = await Promise.all([
     currentBranch(cwd).catch(() => 'HEAD'),
-    runGit(cwd, ['status', '--porcelain=v1', '-z', '--untracked-files=normal']),
+    runGit(cwd, ['status', '--porcelain=v1', '-z', '--untracked-files=all']),
   ])
   return { isRepo: true, branch, entries: parsePorcelainZ(raw) }
 }