feat(qt): the player bar keeps the content pane's gutter on every mode, wider on macOS

Every now-playing bar (New / Classic / Large / Small) is inset by the same
8 px the content pane keeps to its frame — left, right and bottom — behind
a frame-tier backdrop, so the bar's ends line up with the pane's, nothing
in it touches the window edge, and the gutter reads as one continuous
frame with the sidebar rather than a band of raw background. The Large
cover dock lifts with the bar. On macOS the gutter is 16 px: Tahoe's
Liquid Glass windows round their corners far more than before (larger
still around a toolbar) and clip whatever sits inside the curve — the
cover at the bar's left end lost its corner — and Qt has no LayoutRegion
to nest content into the curve, so the margin is the fix.

cc

crates/qbz-qt/qml/shell/AppShell.qml

@@ -252,6 +252,21 @@ Rectangle {
         hostName: QbzOrbit.hostName
     }
 
+    // The player bar's FRAME — the same chrome tier as the sidebar and the
+    // content frame, so the gutter around the inset bar reads as one
+    // continuous frame and never as a band of raw background (the same rule
+    // the content frame documents below). It spans the bar's height plus
+    // the bottom gutter, full width, so the side gutters are covered too.
+    readonly property int npbGutter: Qt.platform.os === "osx" ? theme.npbGutterMac : theme.npbGutter
+    Rectangle {
+        id: npbFrame
+        anchors.left: parent.left
+        anchors.right: parent.right
+        anchors.bottom: parent.bottom
+        height: npb.height + root.npbGutter
+        color: root.ambientOn ? theme.surfaceCardA50 : theme.surfaceCard
+    }
+
     NowPlayingBar {
         id: npb
         // The small seek thumb/hit area extends above the bar by a few pixels.
@@ -261,6 +276,14 @@ Rectangle {
         anchors.left: parent.left
         anchors.right: parent.right
         anchors.bottom: parent.bottom
+        // Inset by the content pane's gutter on the three window edges
+        // (2026-09-13, every mode): the bar's ends line up with the pane's
+        // and nothing in it touches the window edge — wider on macOS, where
+        // the Liquid Glass corner curve ate the cover's corner
+        // (QbzTheme.npbGutterMac).
+        anchors.leftMargin: root.npbGutter
+        anchors.rightMargin: root.npbGutter
+        anchors.bottomMargin: root.npbGutter
         // Mode-aware height (AppShell.slint:396): Small collapses to one
         // header-tall row; New/Classic/Large keep the full 112px.
         height: QbzShell.npbMode === 2 ? theme.npbSmallHeight : theme.npbLargeHeight
@@ -652,7 +675,9 @@ Rectangle {
         // so this width also sets the art size.
         x: 16
         width: 208
-        y: parent.height - QbzShell.largeDockHeight
+        // Flush with the bar's bottom edge, which now sits a gutter above
+        // the window's (npbGutter) — the dock lifts with it.
+        y: npb.y + npb.height - QbzShell.largeDockHeight
         ambientOn: root.ambientOn
     }
 

crates/qbz-qt/qml/shell/NowPlayingBarSmall.qml

@@ -64,8 +64,9 @@ Rectangle {
     // column lands PLAY on the window centre. The breakpoints (39/30/25 at
     // 1366 / 1920) are the SHARED theme token, so this bar and PlayerBar can
     // never drift apart — see QbzTheme.npbSideFrac.
-    // `root.width` IS the window width: the bar is anchored left-to-right on
-    // the shell root, exactly like PlayerBarSmall.slint reads its own root.
+    // `root.width` is the window width minus the two side gutters
+    // (AppShell `npbGutter`): the bar is anchored left-to-right on the shell
+    // root, exactly like PlayerBarSmall.slint reads its own root.
     property real sideFrac: theme.npbSideFrac(root.width)
     property real colCentre: 1.0 - 2.0 * root.sideFrac
     // WIDE = inline horizontal volume slider; NARROW = button-only.

crates/qbz-qt/qml/shell/PlayerBar.qml

@@ -102,8 +102,9 @@ Rectangle {
     // columns EQUAL so the centre column stays dead centre. The breakpoints
     // are the SHARED theme token (QbzTheme.npbSideFrac) — the Small bar reads
     // the same one, so the two bars cannot drift apart.
-    // `root.width` IS the window width: the bar is anchored left-to-right on
-    // the shell root, exactly like PlayerBar.slint reads its own root.
+    // `root.width` is the window width minus the two side gutters
+    // (AppShell `npbGutter`): the bar is anchored left-to-right on the shell
+    // root, exactly like PlayerBar.slint reads its own root.
     property real sideFrac: theme.npbSideFrac(root.width)
     property real colSide: isClassic ? 0.324 : sideFrac
     property real colCentre: 1.0 - 2.0 * colSide

crates/qbz-qt/qml/theme/QbzTheme.qml

@@ -419,6 +419,19 @@ QtObject {
     // Small now-playing bar total height (ShellState.npb-small-height,
     // npb-small-extra is 0 on Linux).
     readonly property int npbSmallHeight: 42
+    /// The gutter the player bar keeps to the window's left, right and
+    /// bottom edges (2026-09-13): the SAME 8 px the content pane keeps
+    /// inside its frame, so the bar's ends line up with the pane's and
+    /// nothing in it touches the window edge.
+    readonly property int npbGutter: 8
+    /// macOS only: Tahoe's Liquid Glass windows round their corners far
+    /// more than before (Apple: toolbar windows take a larger radius that
+    /// "can clip content that sits close to the edge of the window";
+    /// estimates run from ~12-16 pt for titlebar-only windows to 50 px+
+    /// with a toolbar) and the cover at the bar's left end lost its corner.
+    /// Qt has no LayoutRegion to nest content into the curve, so the bar
+    /// simply keeps a wider gutter there.
+    readonly property int npbGutterMac: 16
     // Every other bar mode (New / Classic / Large) — AppShell.slint:396.
     // The Large dock's sidebar reservation subtracts this, so it must be the
     // SAME value the shell pins the bar to.