* feat(#363): add descriptive text to loading spinners - Updates LoadingState composable to accept optional subtitle - Shows 'Fetching model providers...' on ModelScreen - Shows 'Loading channels...' on ChannelsScreen - Removes dead/unreachable CircularProgressIndicator from ModelScreen * fix(#363): pass loading_state_subtitle_models string to LoadingState --------- Co-authored-by: M57 <hy4ri@users.noreply.github.com>