Build a small macOS utility for checking file SHA-256 values.
Let me choose a local file, including a filename containing spaces.
Show the filename, byte count and lowercase SHA-256 digest.
Provide Clear, Copy digest and Save result as plain text.
Clear must remove the current file and result.
When I choose another file, never keep the previous digest labeled as current.
Compute over file bytes, including any final newline.
Verify abc.txt and renamed-abc.txt return the same digest.
Verify abc-newline.txt returns the separate expected digest.
Include run instructions and a report of the checks performed.