Updated DigitalData.Core.Abstraction.Application from 1.4.0 to 1.6.0 across all relevant project files and package configs. Also updated DigitalData.Core.Infrastructure from 2.4.5 to 2.6.1 in EnvelopeGenerator.Infrastructure.csproj. No other code changes were made.
Added full implementation for CreateAnnotationCommand and its handler:
- Introduced `PSPDFKitInstantJSON` property to the command
- Injected repositories for `Signature` and `Annotation`
- Implemented query filtering for Envelope and Receiver
- Added annotation creation from parsed PSPDFKit JSON
- Created helper method `ParsePSPDFKitInstantJSON` for JSON parsing
