Add desktop app service and VM dev session tooling

Introduces a new `core/applications` QML/C++ module (`Nebula.Applications`) to discover `.desktop` entries, expose filterable application models, and launch installed apps safely from the shell. The desktop launcher now uses real installed apps with themed icon loading and fallback glyphs, adds output-aware surface sizing via `OutputTracker`, and wires in image/icon providers. It also adds VMware-focused Sway/shell wrapper scripts, updates Sway config/session env defaults, and refreshes README docs to document the new development flow and Desktop 0.1 behavior.

shells/desktop/shell/qml/surfaces/TopBarSurface.qml

@@ -6,11 +6,15 @@ import Nebula.UI
 Window {
     id: root
 
+    readonly property int outputWidth: OutputTracker.width > 0
+        ? OutputTracker.width
+        : (screen && screen.width > 0 ? screen.width : Screen.width)
+
     title: qsTr("Nebula Top Bar")
     color: "transparent"
     flags: Qt.FramelessWindowHint | Qt.WindowDoesNotAcceptFocus
     visible: true
-    width: Screen.width
+    width: outputWidth
     height: Theme.topBarHeight
 
     LayerShell.Window.scope: "nebula-topbar"