* Removed `dbContextOptions` parameter from `AddEnvelopeGeneratorInfrastructureServices`
* Moved `AddDbContext` registration into `Config` class with overloads for both `Action<DbContextOptionsBuilder>` and `Action<IServiceProvider, DbContextOptionsBuilder>`
* Simplified service registration flow and improved extensibility
- Wrapped `using` directives with `#if NET` and `#elif NETFRAMEWORK`
- Applied conditional inheritance for `IUserManagerDbContext` and `IMailDbContext`
- Made `EmailOut` DbSet and triggers only available in `NET` builds
- Adjusted `_logger` nullability for NET vs NETFRAMEWORK targets
- Ensured `modelBuilder.ConfigureUserManager()` only runs in NET builds
- Umschlossene Repository- und Executor-Registrierungen mit `#if NET`, um die Kompatibilität zwischen .NET und .NET Framework sicherzustellen
- Hinzufügen des Abschnitts `#elif NETFRAMEWORK` für frameworkspezifische Importe
- Verschieben der SQLExecutor- und Dapper-Typzuordnung unter bedingte Kompilierung
- Anpassen der Methodensignaturen zur Unterstützung bedingter nullbarer Parameter
- Introduced Page(Action<PdfPage>) method to apply design logic to every page in the document
- Simplified Background method by replacing per-page iteration with new Page overload
- Improved readability and maintainability by removing duplicate page loop logic
- Added `System.Linq` import to enable distinct and ordered page index selection
- Applied `ConcatMatrix` transformation once per page instead of per signature
- Improved performance and reduced redundant operations in `Background` method
- Introduced `Edit` extension methods for `Stream` and `byte[]` to allow
in-place PDF modifications via a `PdfDocument` action.
- Supports both .NET and .NET Framework projects.
- Ensures proper disposal of streams and PdfDocument instances.
