Added client abstractions for backend functions

src/WorkTime.Mobile/Platforms/Android/MainApplication.cs

@@ -0,0 +1,12 @@
+using Android.App;
+using Android.Runtime;
+
+namespace WorkTime.Mobile;
+
+[Application]
+public class MainApplication : MauiApplication {
+    public MainApplication(IntPtr handle, JniHandleOwnership ownership)
+        : base(handle, ownership) { }
+
+    protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
+}