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/main.cpp

@@ -1,11 +1,48 @@
+#include "DesktopIconProvider.hpp"
+
 #include <LayerShellQt/Shell>
 
+#include <QCoreApplication>
+#include <QDir>
 #include <QGuiApplication>
+#include <QIcon>
 #include <QQmlApplicationEngine>
 #include <QQuickWindow>
 #include <QUrl>
 #include <QtGlobal>
 
+namespace {
+
+void initializeIconTheme()
+{
+    if (QIcon::themeName().isEmpty()) {
+        const QStringList candidates = {
+            QStringLiteral("Adwaita"),
+            QStringLiteral("Yaru"),
+            QStringLiteral("ubuntu-mono-dark"),
+            QStringLiteral("breeze"),
+            QStringLiteral("hicolor"),
+        };
+
+        const QStringList searchPaths = QIcon::themeSearchPaths();
+        for (const QString &theme : candidates) {
+            for (const QString &root : searchPaths) {
+                if (QDir(root + QLatin1Char('/') + theme).exists()) {
+                    QIcon::setThemeName(theme);
+                    break;
+                }
+            }
+            if (!QIcon::themeName().isEmpty())
+                break;
+        }
+    }
+
+    if (QIcon::fallbackThemeName().isEmpty())
+        QIcon::setFallbackThemeName(QStringLiteral("hicolor"));
+}
+
+} // namespace
+
 int main(int argc, char *argv[])
 {
     LayerShellQt::Shell::useLayerShell();
@@ -16,10 +53,12 @@ int main(int argc, char *argv[])
     app.setOrganizationName(QStringLiteral("NebulaOS"));
     app.setDesktopFileName(QStringLiteral("org.nebulaos.shell"));
 
+    initializeIconTheme();
     QQuickWindow::setDefaultAlphaBuffer(true);
 
     QQmlApplicationEngine engine;
     engine.addImportPath(QStringLiteral("qrc:/qt/qml"));
+    engine.addImageProvider(QStringLiteral("desktopicon"), new DesktopIconProvider);
 
     QObject::connect(
         &engine,