fix(qbz-slint): match current QBZ Discover Home

Corrections from testing feedback:
- Remove the greeting — the current QBZ discovery view has no greeting,
  only the tab selector. Drops HomeState.greeting and the chrono dep.
- Quality badge is now the icon-only badge (hi-res.svg, or cd.svg in a
  framed square), not a numeric text pill. AlbumCardItem carries a
  quality tier instead of a quality string.
- Tighten the album card: deterministic 274px height, title and artist
  in a 2px-spaced stack — removes the large gap between them.
- SectionRow no longer scrolls vertically (vertical-scrollbar-policy
  always-off, height pinned to the card height).
- Artwork is downscaled to 264px on decode instead of holding ~600px
  source textures.

cc

crates/qbz-slint/ui/discover/HomeView.slint

@@ -49,14 +49,6 @@ export component HomeView inherits Rectangle {
             spacing: 28px;
             alignment: start;
 
-            Text {
-                text: HomeState.greeting;
-                visible: HomeState.greeting != "";
-                color: Theme.text-primary;
-                font-size: 26px;
-                font-weight: Typography.semibold;
-            }
-
             HorizontalLayout {
                 alignment: start;
                 Rectangle {