fix(slint): toolbar vertical align, header toggle, queue menu clicks

The Discover toolbar's side layouts had no explicit height, so they
filled the 56px bar and y resolved to 0 — the tab pill, genre filter
and gear stuck to the top instead of centering. Both now carry
height = preferred-height.

The header sidebar toggle dropped from a 19px to a 14px icon: it now
matches the nav-tab icon size and tint, and the 30px box centers it
on whole pixels (was 5.5px → blurry).

The queue row's click TouchArea was declared after the content, so it
sat on top and ate the context-menu button's clicks — the [...] just
skipped to the track. It is now declared before the content, so the
menu button keeps its own clicks.

cc

crates/qbz-slint/ui/shell/QueueSidebar.slint

@@ -128,6 +128,17 @@ component QueueRow inherits Rectangle {
     background: ta.has-hover ? Theme.surface-hover : transparent;
     border-radius: Radius.sm;
 
+    // Declared before the content so the context-menu button (which has
+    // its own TouchArea) renders on top and keeps its own clicks. A row
+    // TouchArea declared after the content would sit on top and eat the
+    // menu-button clicks — making the [...] just skip to the track.
+    ta := TouchArea {
+        mouse-cursor: pointer;
+        clicked => {
+            root.clicked();
+        }
+    }
+
     HorizontalLayout {
         padding-left: Spacing.sm;
         padding-right: Spacing.xs;
@@ -226,15 +237,6 @@ component QueueRow inherits Rectangle {
         }
     }
 
-    ta := TouchArea {
-        // The menu trigger sits above this area and consumes its own
-        // clicks, so a row click never doubles as a menu open.
-        mouse-cursor: pointer;
-        clicked => {
-            root.clicked();
-        }
-    }
-
     // Per-track context menu — 1:1 with the Tauri queue track menu.
     // Only "Remove from queue" is wired; the rest are placeholders.
     track-menu := PopupWindow {