Add widget annotation and update stroke color

Updated `createAnnotations` to initialize a `PSPDFKit.Annotations.WidgetAnnotation` object, enabling the creation of widget annotations.

Modified `ctx.strokeStyle` in `createAnnotationFrameBlob` to use 'darkblue' instead of 'darkgray', improving the visual appearance of the annotation frame.

EnvelopeGenerator.Web/wwwroot/js/annotation.js

@@ -13,7 +13,7 @@ async function createAnnotations(document, envelopeId, receiverId) {
         const id = generateId(envelopeId, receiverId, element.id, 'signature');
 
         const boundingBox = new PSPDFKit.Geometry.Rect(annotParams.signature);
-        
+
         const annotation = new PSPDFKit.Annotations.WidgetAnnotation({
             id: id,
             pageIndex: page,
@@ -273,7 +273,7 @@ async function createAnnotationFrameBlob(receiverName, receiverSignature, timest
     ctx.moveTo(30 * scale, 50 * scale)
     ctx.lineTo(signatureLength, 50 * scale)
 
-    ctx.strokeStyle = 'darkgray'
+    ctx.strokeStyle = 'darkblue'
     ctx.stroke()
 
     ctx.fillStyle = 'black'