add Windows build readme

Photomator/Photomator.csproj

@@ -19,6 +19,7 @@
   </ItemGroup>
 
   <Target Name="PreBuild" BeforeTargets="PreBuildEvent">
+    <Message Text="=== Building Photomator $(GitTag)... ===" Importance="high" />
     <RemoveDir Directories="$(PublishDir)" />
     <Message Text="=== Compiling extra resources... ===" Importance="high" />
     <Exec Command="glib-compile-resources --sourcedir ./Resources ./Resources/de.cantorgymnasium.Photomator.gresource.xml --target=$(OutDir)/de.cantorgymnasium.Photomator.gresource" />

README.md

@@ -1,3 +1,23 @@
 # Photomator
 
 Desktop-Anwendung zum Konvertieren und Schrumpfen von Bildern für die Verwendung im Web.
+
+## Build
+
+### Windows
+
+- install msys2 (mingw-w64) -> libadwaita, gtk4, libwebp
+- install .NET 8.0
+- install Git for Windows
+- add .NET 8.0 and mingw-w64 to PATH
+
+```powershell
+git clone https://git.cantorgymnasium.de/gcg/photomator
+
+cd photomator/Photomator
+
+dotnet restore
+dotnet publish -r win-x64
+```
+
+The installer will be located under `Photomator\bin\Release\net8.0\win-x64\publish`.