feat(qbz-qt): phase 16 — card overlays everywhere + window-centered modals

Overlay opacity bindings referenced a nonexistent parent chain — all
card overlays evaluated invisible. Fixed per family: LibTrackCard
(scrim + fav/play/more row, full Slint menu), LibArtistCard rewrite
(circle-clipped scrim, play + more; play_artist with Popular-tracks
first and studio-discography fallback), LibPlaylistCard overlay fixed,
LibLabelCard verified overlay-less like the Slint. Modals: shared
AppShell-level layer (full-window scrim, window-centered panel)
replacing the view-local content-frame-centered ones.

km

crates/qbz-qt/qml/assets/icons/accent/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#4285f4" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>

crates/qbz-qt/qml/assets/icons/black/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#000000" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>

crates/qbz-qt/qml/assets/icons/favorite/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#ef4444" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>

crates/qbz-qt/qml/assets/icons/muted/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#888888" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>

crates/qbz-qt/qml/assets/icons/primary/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>

crates/qbz-qt/qml/assets/icons/secondary/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#cccccc" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>

crates/qbz-qt/qml/assets/icons/warning/thumbs-down.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="#fbbf24" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M17 14V2" />
+  <path d="M9 18.12 10 14H4.17a2 2 0 0 1-1.92-2.56l2.33-8A2 2 0 0 1 6.5 2H20a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2h-2.76a2 2 0 0 0-1.79 1.11L12 22a3.13 3.13 0 0 1-3-3.88Z" />
+</svg>