The `<TargetFrameworks>` property in `EnvelopeGenerator.API.csproj` was downgraded from `net9.0` to `net8.0`. Conditional package references were added for `Microsoft.AspNetCore.OpenApi` and `Microsoft.EntityFrameworkCore.SqlServer` to support both `net8.0` and `net9.0`.
Added `itext` and `itext.bouncy-castle-adapter` (version 8.0.5) as new dependencies. Updated the project to include a reference to `EnvelopeGenerator.PdfEditor.csproj`. Removed unconditional `Microsoft.AspNetCore.OpenApi` reference and replaced it with conditional references based on the target framework.