Promote shell to its own top-level directory

shell/Ui/PanelSectionHeader.qml

@@ -0,0 +1,17 @@
+import QtQuick
+
+// Small-caps-style label that introduces a panel section ("DNS provider",
+// "Wi-Fi networks", "Output device", "Paired devices"). Sits between a
+// PanelSeparator and the content rows.
+Text {
+  id: root
+
+  property color foreground: "#cacccc"
+  property string fontFamily: "JetBrainsMono Nerd Font"
+  property real fontSize: 10
+
+  color: Qt.darker(foreground, 1.4)
+  font.family: fontFamily
+  font.pixelSize: fontSize
+  font.bold: true
+}