v2.68.10

• Track details now render directly from the latest prop: title, artist, cover, and playback progress are never gated on album-color extraction.
• The extracted gradient is independent visual state. While the next cover's colors are pending, the outgoing gradient remains painted instead of dropping to bare paper.
• AlbumGradientBackdrop paints gradients on stacked layers because gradient stacks are not reliably interpolable. The incoming layer fades over the outgoing one, then removes spent layers on animationend; the surface and blurred glow dissolve together.
• The background keeps TIMING_SLOW with EASING_DEFAULT, a plain ease rather than a spring. Reduced-motion CSS collapses the animation to an effectively instant swap.
• Removed the 1.5s handoff timeout, deferred displayTrack, and WAAPI opacity settle. Only the background animates now.
• Added tests proving that next-track content renders while extraction is unresolved and that the previous gradient persists until the replacement resolves.

Browser verification used an intentional 900ms delay on the incoming album-art request. The new title committed 3.9ms after the track prop changed (worst of dark/light measurements), while the old gradient remained fully painted until the new one crossfaded in. Old main showed a bare card during the same delayed extraction window.