Assemble a Customer Proposal

Tested on Windows x64 with Arial and the exact .NET SDK8.0.427 in global.json; uses Aspose.Slides.NET26.10.0 (restored from NuGet), and an appropriate license for full-content assertions.
Set ASPOSE_LICENSE_PATH to your license; then run dotnet run --project Example.csproj --configuration Release

Assemble a customer proposal from a synthetic product catalog and a JSON selection. The complete project creates a cover, copies the chosen product slides in request order, and saves an editable deck and a PDF. The original catalog remains unchanged.
Outputs appear in the working directory.
