TaskyPad 1.0.3

Add "No notes" message and update version to 1.0.3

Added a `TextBlock` in `MainWindow.xaml` to display a message
when there are no notes. The message is styled and toggled
based on the presence of notes in `MainWindow.xaml.cs`.

Updated `AssemblyVersion` in `TaskyPad.csproj` from 1.0.2 to
1.0.3 to reflect the new feature. Minor structural changes
were also made to the project file.