New shared ReleaseDescription control renders the blurb in a uniform themed block
below the hero/header; null/whitespace renders nothing, with no layout artifact.
Add optional Ambient slot to ReleaseDetailScaffold (full-bleed layer behind content; absent = no regression). Cut mounts it + popover; Session mounts the engine directly behind its hero; Mix swaps its inline knob-bar for the lava-lamp popover.
Header Play loads full album at index 0; row play loads at that row's index with same-track
toggle preserved; null-safe cascade fallback to direct SelectTrackStreaming when queue absent.
Compose ReleaseDetailScaffold via Header + BodyContent slots for the Cut
album view: left meta + Play/Share, right theme-bordered cover, TrackNumber-
ordered track list with per-row play. CutDetailBase carries the multi-track
prerender bridge.
daniel-c-harvey