- Added Microsoft.Extensions.Hosting.WindowsServices package - Added builder.Host.UseWindowsService() to Program.cs - Service can now run either as console app or Windows Service
- Services/ExcelToPdfService.cs: core conversion logic (XlsIORenderer) - Controllers/ExcelToPdfController.cs: REST API endpoints * POST /api/ExcelToPdf/convert (file upload) * POST /api/ExcelToPdf/convert-by-path (server path) * GET /api/ExcelToPdf/health - Program.cs: minimal API setup, 50MB upload limit - appsettings.json: port 5200, Syncfusion license - Syncfusion 21.1.37 (XlsIO + Pdf + XlsIORenderer) - Binary signed: Azure Trusted Signing (Private Trust)