Reset isCommentsExpanded and commentsFrame on the NavigationCoordinator
directly when the portrait panel is dismissed, since PortraitDetailsPanel
owns its own @State that doesn't sync back through .onChange during dismiss.
Also track comments overlay frame via GeometryReader so the dismiss gesture
can allow swipes outside the comments area instead of blanket-blocking.
Playlists only loaded the first page of videos. Add full pagination for
both Invidious and Piped playlist endpoints (public and authenticated).
Deduplicate Invidious results by playlist index to handle its overlapping
page windows. Also fix URL encoding in Invidious login to use strict
form-encoding charset.
