Add project restore files and NuGet cache for GsaViewer

- Created project.nuget.cache to store NuGet package cache information.
- Added project.packagespec.json to define project restore settings and dependencies.
- Included rider.project.restore.info for Rider IDE integration.

app.manifest

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <!-- This manifest is used on Windows only.
+       Don't remove it as it might cause problems with window transparency and embedded controls.
+       For more details visit https://learn.microsoft.com/en-us/windows/win32/sbscs/application-manifests -->
+  <assemblyIdentity version="1.0.0.0" name="GsaViewer.Desktop"/>
+
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- A list of the Windows versions that this application has been tested on
+           and is designed to work with. Uncomment the appropriate elements
+           and Windows will automatically select the most compatible environment. -->
+
+      <!-- Windows 10 -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
+    </application>
+  </compatibility>
+</assembly>