The model was reported as ready while the AI runtime was actually
unreachable, and the Download action stayed visible afterwards.
Distinguish model-downloaded from runtime-available in
layaStatusPresentation, derive the Download action from the real
combined state, and align Settings and ChannelList rendering on that
single source of truth. Cover the combined status cases with tests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
d253642dec