feat: add pane component

AppPane.qml

@@ -0,0 +1,22 @@
+import QtQuick
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
+
+T.Pane {
+    id: control
+
+    implicitWidth: Math.max(implicitBackgroundWidth + leftInset + rightInset,
+                            contentWidth + leftPadding + rightPadding)
+    implicitHeight: Math.max(implicitBackgroundHeight + topInset + bottomInset,
+                             contentHeight + topPadding + bottomPadding)
+
+    padding: 12
+
+    background: Rectangle {
+        anchors.fill: parent
+        color: Theme.card
+        radius: Theme.radius
+        border.color: Theme.softBorder
+        border.width: 1
+    }
+}

CMakeLists.txt

@@ -29,6 +29,7 @@ set(plain_qml_files
   AppLink.qml
   AppWarning.qml
   AppMenu.qml
+  AppPane.qml
 )
 set(qml_singletons
   Fonts.qml