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/src/OutputTracker.hpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <QObject>
+#include <QPointer>
+#include <QQmlEngine>
+#include <QScreen>
+#include <QtQml/qqmlregistration.h>
+
+class QJSEngine;
+
+class OutputTracker : public QObject
+{
+    Q_OBJECT
+    QML_ELEMENT
+    QML_SINGLETON
+    Q_PROPERTY(int width READ width NOTIFY geometryChanged)
+    Q_PROPERTY(int height READ height NOTIFY geometryChanged)
+    Q_PROPERTY(qreal devicePixelRatio READ devicePixelRatio NOTIFY geometryChanged)
+    Q_PROPERTY(QString name READ name NOTIFY geometryChanged)
+
+public:
+    explicit OutputTracker(QObject *parent = nullptr);
+    static OutputTracker *create(QQmlEngine *engine, QJSEngine *scriptEngine);
+
+    int width() const;
+    int height() const;
+    qreal devicePixelRatio() const;
+    QString name() const;
+
+signals:
+    void geometryChanged();
+
+private:
+    void bindScreen(QScreen *screen);
+    void logGeometry() const;
+
+    QPointer<QScreen> m_screen;
+};