Initial analysis: Update .NET framework to 8.0 and fix Program.cs for compatibility

Co-authored-by: CalinL <10718943+CalinL@users.noreply.github.com>

Author: Copilot

src/webapp01/Program.cs

@@ -19,8 +19,7 @@
 
 app.UseAuthorization();
 
-app.MapStaticAssets();
-app.MapRazorPages()
-   .WithStaticAssets();
+app.UseStaticFiles();
+app.MapRazorPages();
 
 app.Run();

src/webapp01/webapp01.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>net9.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <UserSecretsId>7f0355f0-e3cb-4a1e-bf2d-0431db9b93f8</UserSecretsId>