Video queue / "play next" accessible in the portrait player

[CodeSculptor]

Summary

User request: first-class support for queueing videos to play next from the portrait UI. The upstream/landscape player already has a Playback Queue dialog (AppDialogUtil.showPlaybackQueueDialog, action R.id.action_playback_queue); the ask is to make queueing convenient in portrait — the user relies heavily on this workflow (currently uses PipePipe for it).

User's words

I would love a playlist feature to me implemented if possible, I really love queueing videos up.
I queue to make videos play up next like this one [screenshot of the landscape playback-queue dialog]

Proposed

• Surface the existing playback-queue view in the portrait player (e.g. a control in the portrait chrome, or a portrait-styled panel like the new "Save to playlist" sheet).
• Optionally an "add to queue / play next" affordance on video rows.

Notes

• Distinct from the "Save to playlist" (add current video to a saved playlist) panel already added to the portrait/Shorts nav bar — this is the transient up-next queue, not saved playlists.
• Reported alongside the "Save to playlist" portrait panel work.