feat(annotation): extend mapSignature to include FRAME annotations

- Updated `mapSignature` function to also map image/frame annotations.
- For each annotation with `description === 'FRAME'`, add `name` and `value` based on corresponding attachment.
- Preserves existing mapping of form fields, filtering out labels.
- Ensures signature data and associated frames are returned in a structured object.

EnvelopeGenerator.Web/wwwroot/js/annotation.js

@@ -316,6 +316,11 @@ function mapSignature(iJSON) {
             field.elementId = Number(nameParts[2]);
             field.name = nameParts[3];
             return field;
+        }),
+        frames: iJSON.annotations.filter(annot => annot.description === 'FRAME').map((annot) => {
+            annot.name = annot.description.toLowerCase();
+            annot.value = iJSON.attachments[annot.imageAttachmentId]?.binary || null;
+            return annot;
         })
     };
 }