The preview backend never received a volume — clips played at the crate
default (0.7) regardless of the slider, even muted. The session now sets
the preview volume from the app store (mute → 0) before the first load and
mirrors it live while the modal is open; the debug overlay's PREVIEW row
exposes the backend's resting volume as proof.
The player-bar volume (and fallback seek) fill is now always the accent
color — matching the waveform scrubber's played region — stepping up to
the hover shade on hover instead of white-until-hover.
Also syncs package-lock to the soulstream name + alpha version.