Introduced the `ResultFilePath` property in the `ZugferdInvoice` model to store the path of generated result PDFs. Added a new service, `PdfResultPackageService`, to create result PDFs by converting the original PDF to PDF/A-3b format and attaching a report file. Updated `Upload.cshtml` and `Upload.cshtml.cs` to handle and display the `ResultFilePath`.
Created a migration to add the `ResultFilePath` column to the database. Updated `Program.cs` to register the new service and added configuration sections in `appsettings.json` for input and output directories. Enhanced error handling and logging for better traceability.
The `ConnectionStrings` section in the `appsettings.json` file was updated. The `EcmContext` connection string, previously an empty string, was replaced with a connection string pointing to a SQL Server instance.
The new connection string includes the server name, database name, user ID, password, and a flag to trust the server certificate. This change enables the application to connect to the specified SQL Server database.
