Status() reports a wholly untracked directory as a plain file path, so callers can't tell "newdir/" from a file named "newdir" #150

What's wrong

The default untracked mode is GitUntrackedFilesMode.Normal. In that mode, git collapses a directory with no tracked files to a single record, ? newdir/, with a trailing slash. The collapse itself is documented on the enum.

However, Parsing/GitStatusParser.cs (ReadPathOnlyEntry, around lines 76 and 220) converts the path with GitParseValues.ToRelativeFilePath, which loses the trailing /. GitStatusEntry has no directory flag either. The entry is typed as a RelativeFilePath, and nothing indicates that it is a directory. Ignored (!) records have the same problem.

Failure scenario

Commit a.txt, then create newdir/x.txt. Status() returns a single entry: Path='newdir', Untracked. That is exactly what an untracked file named newdir would produce.

• A "discard untracked files" feature that calls File.Delete(entry.Path) throws or does nothing.
• A UI can't show a folder or offer to expand it.

An untracked nested repository or submodule checkout shows up the same way.

This was reproduced with a scratch integration test through the public Status() API, which printed STATUS 'newdir' Untracked.

Suggested fix / acceptance criteria

• Detect the trailing / on ? and ! records and surface it, for example with bool IsDirectory on GitStatusEntry, or with a directory-path type.
• Tests:
  • in default mode, Status() over an untracked directory reports an entry marked as a directory;
  • an untracked file with the same name is not marked as a directory.