The detail sheet always answers 'who maintains this?': one
selectable line per maintainer from the store index's new
maintainers list, or an honest 'not specified' when the index
names nobody (StoreMaintainersSection, public for the widget
tests). The install trust gate carries the same fact when
present and stays terse otherwise. DE+EN; dialog-harness proof
captured with the maintainer row.
Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>
