A label that displays the working directory, condensed to fit.
The tail of a path is the part users read, so directory components are
collapsed from the middle outward (see :func:condense_path) rather than
clipping the end the way CSS text-overflow: ellipsis does. The widget
sizes to the full path but is capped by .status-cwd's max-width, so
render always sees the real budget in content_size. The untruncated
path is always available as the widget's tooltip.
