fix: stabilize playback memory, local library sync and Qt settings

Add shared playback memory profiles, bounded disk-backed playback and storage
selection for desktop and daemon. Preserve gapless during streaming-only playback
and provide explicit cache eviction with playback confirmation.

Stop watcher read events and unchanged scans from rebuilding the local catalog.
Restore playlist/sidebar updates, folder availability feedback and player layout.
Add appearance presets and a radio-based cache settings panel with translated
trade-offs, plus consistent clipboard menus across visible Qt text editors.

Validate with Rust regressions, QML interaction tests, isolated release startup
and idle-library checks; extend the shared local and CI gates.

cx

crates/qbz-qt/qml/views/AlbumListRow.qml

@@ -66,7 +66,8 @@ Rectangle {
     readonly property bool pulled: root.item.qobuzUnavailable === true
     readonly property int cacheStatus: root.item.cacheStatus !== undefined
         ? root.item.cacheStatus : 0
-    readonly property bool pulledDead: root.pulled && root.cacheStatus !== 3
+    readonly property bool pulledDead: (root.pulled && root.cacheStatus !== 3)
+        || root.item.sourceUnavailable === true
     /// `modifiers` rides straight off the mouse event: Shift is what turns
     /// a click into a range (controls/SelectionModel.qml).
     signal toggleSelect(int modifiers)
@@ -123,7 +124,7 @@ Rectangle {
     /// below all resolve a catalog id.
     readonly property bool catalogRow: {
         var src = root.item.source || ""
-        return src !== "local" && src !== "plex"
+        return src === "" || src === "qobuz"
     }
 
     function menuEntries() {