Updated the `Handle` method in multiple classes implementing
`IPipelineBehavior<SignCommand, Unit>` to pass the `cancellationToken`
parameter to the `next()` method. This change ensures consistent
propagation of the `cancellationToken` through the pipeline, enabling
proper handling of cancellation requests during asynchronous operations.
Modified files:
- AnnotationBehavior.cs
- DocStatusBehavior.cs
- HistoryBehavior.cs
- SendSignedMailBehavior.cs
Updated namespaces from `Signature` to `Signatures` for consistency and clarity across the application. Simplified pipeline behavior registrations in `DependencyInjection.cs` by using shorter references. Added `Microsoft.Extensions.Configuration` to `DependencyInjection.cs` to support configuration functionality. Ensured all references to `SignCommand` and related behaviors align with the new namespace structure.
