feat(pdf): implement annotation burning logic in BurnPdfCommandHandler

- Added full implementation of BurnElementAnnotsToPDF method
- Integrated PdfEditor for background rendering
- Added annotation handling for form fields, images, and ink types
- Included error handling for PDF loading and saving
- Removed unused DigitalData.Core.Abstractions namespace

EnvelopeGenerator.Application/EnvelopeGenerator.Application.csproj

@@ -46,6 +46,7 @@
 
 	<ItemGroup>
 		<ProjectReference Include="..\EnvelopeGenerator.Domain\EnvelopeGenerator.Domain.csproj" />
+		<ProjectReference Include="..\EnvelopeGenerator.PdfEditor\EnvelopeGenerator.PdfEditor.csproj" />
 	</ItemGroup>
 
 	<ItemGroup>
@@ -165,4 +166,8 @@
 	  </PackageReference>
 	</ItemGroup>
 
+	<ItemGroup>
+	  <Folder Include="Exceptions\" />
+	</ItemGroup>
+
 </Project>