feat: Auto-copy Blazor client wwwroot on build

- Add CopyBlazorClientWwwroot target to QuantEngine.Web.csproj
- Automatically copies Blazor WebAssembly output to server wwwroot
- Fixes missing _framework files and MIME type errors
- Ensures static files are always up-to-date after build
- Resolves Blazor module loading failures

Before: Manual wwwroot copy needed after each build
After: Automatic copy on every dotnet build

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/dotnet/QuantEngine.Web/QuantEngine.Web.csproj

@@ -28,4 +28,13 @@
     <BlazorDisableThrowNavigationException>true</BlazorDisableThrowNavigationException>
   </PropertyGroup>
 
+  <!-- Auto-copy Blazor client wwwroot to server wwwroot after build -->
+  <Target Name="CopyBlazorClientWwwroot" AfterTargets="Build">
+    <ItemGroup>
+      <ClientWwwrootFiles Include="Client\bin\$(Configuration)\net10.0\wwwroot\**\*" />
+    </ItemGroup>
+    <Copy SourceFiles="@(ClientWwwrootFiles)" DestinationFiles="@(ClientWwwrootFiles->'wwwroot\%(RecursiveDir)%(Filename)%(Extension)')" />
+    <Message Text="✅ Copied Blazor client wwwroot to server wwwroot" Importance="high" />
+  </Target>
+
 </Project>