v0.4.0

Changed

• Reworked the interface: the left sidebar is replaced by a top band that shows
  one view at a time: commits (list beside the selected commit's message),
  files, or annotations. Shift-Tab cycles the band view; Tab toggles focus
  between the band and the diff.
• Annotation editor key hints are styled consistently with the diff help line
  (bold, accented keys). The redundant (ctrl-t) is dropped from the box title.

Fixed

• Annotations on deleted lines now render inline in the diff. They were filtered
  out after saving, so the block showed only while the editor was open. In split
  view an old-side block hangs under the left cell with the column divider
  intact.