fix(slint): instant local queue, mouse nav buttons, narrower toolbar controls

- Local Library Tracks: build the play queue from the already-loaded rows
  (instant) instead of re-querying the DB + filling covers on every click.
- Mouse back/forward buttons now drive history nav over track rows and album
  cards (a TouchArea swallows them, so each interactive surface forwards them;
  the AppShell catcher only saw the gaps).
- ExpandableSearch open width trimmed 20px (no longer rides over left controls
  on small screens).
- QbzSelect toolbar (Group/Sort/filter) trimmed 40px total.

cc

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

@@ -13,7 +13,7 @@ import { Theme } from "../foundation/semantic-colors.slint";
 import { Typography } from "../foundation/typography.slint";
 import { Radius } from "../foundation/radius.slint";
 import { Spacing } from "../foundation/spacing.slint";
-import { AlbumCardItem } from "../state.slint";
+import { AlbumCardItem, NavState } from "../state.slint";
 import { QbzIcon } from "../primitives/QbzIcon.slint";
 import { QualityBadge } from "../primitives/QualityBadge.slint";
 import { ContextMenu } from "../primitives/ContextMenu.slint";
@@ -56,6 +56,16 @@ component OverlayButton inherits Rectangle {
         clicked => {
             root.clicked();
         }
+        // Forward the mouse back/forward buttons to history nav (a TouchArea
+        // swallows them, so they never reach the AppShell catcher).
+        pointer-event(e) => {
+            if (e.kind == PointerEventKind.down && e.button == PointerEventButton.back) {
+                NavState.request-back();
+            }
+            if (e.kind == PointerEventKind.down && e.button == PointerEventButton.forward) {
+                NavState.request-forward();
+            }
+        }
     }
 }
 

crates/qbz-slint/ui/primitives/ExpandableSearch.slint

@@ -12,7 +12,9 @@ import { QbzIcon } from "QbzIcon.slint";
 
 export component ExpandableSearch inherits Rectangle {
     in property <string> placeholder: "Search…";
-    in property <length> max-open-width: 216px;
+    // Trimmed 20px so the open field doesn't ride over the controls to its
+    // left on small screens.
+    in property <length> max-open-width: 196px;
     in-out property <bool> open: false;
     in-out property <string> query;
     // Bootstrap-style small variant. Default is the standard size.

crates/qbz-slint/ui/primitives/QbzSelect.slint

@@ -53,8 +53,8 @@ export component QbzSelect inherits Rectangle {
     callback selected(int);
 
     // Toolbar (sm) selects — Group / Sort / filter — were unnecessarily wide;
-    // trim 20px from the effective width (button + list).
-    private property <length> eff-width: root.menu-width - (root.sm ? 20px : 0px);
+    // trim 40px from the effective width (button + list).
+    private property <length> eff-width: root.menu-width - (root.sm ? 40px : 0px);
     // Resolved width of the open list.
     private property <length> list-width:
         root.popup-width > root.eff-width ? root.popup-width : root.eff-width;

crates/qbz-slint/ui/primitives/TrackRow.slint

@@ -18,7 +18,7 @@
 import { Theme } from "../foundation/semantic-colors.slint";
 import { Typography } from "../foundation/typography.slint";
 import { Radius } from "../foundation/radius.slint";
-import { TrackItem, DragActions, NowPlayingState } from "../state.slint";
+import { TrackItem, DragActions, NowPlayingState, NavState } from "../state.slint";
 import { QbzIcon } from "QbzIcon.slint";
 import { TrackPlayCell } from "TrackPlayCell.slint";
 import { TrackContextMenu } from "TrackContextMenu.slint";
@@ -81,6 +81,15 @@ export component TrackRow inherits Rectangle {
         property <length> down-y;
         property <bool> dragging: false;
         pointer-event(e) => {
+            // The mouse back/forward buttons drive history nav. A TouchArea
+            // swallows these (they never reach the AppShell catcher), so each
+            // interactive row forwards them itself.
+            if (e.kind == PointerEventKind.down && e.button == PointerEventButton.back) {
+                NavState.request-back();
+            }
+            if (e.kind == PointerEventKind.down && e.button == PointerEventButton.forward) {
+                NavState.request-forward();
+            }
             if (e.kind == PointerEventKind.down) {
                 ta.down-x = root.absolute-position.x + ta.mouse-x;
                 ta.down-y = root.absolute-position.y + ta.mouse-y;