refactor(annotations): include bounding box info in mapped signature fields

- Added `x`, `y`, `width`, and `height` properties to form field mapping in `mapSignature`.
- Preserves original form field values while enriching them with annotation coordinates.
- No functional changes to annotation creation, deletion, or validation.

EnvelopeGenerator.Web/wwwroot/js/annotation.js

@@ -321,11 +321,16 @@ function mapSignature(iJSON) {
         // formFields
         ...iJSON.formFieldValues.filter(field => !field.name.includes("label")).map((field) => {
             const nameParts = field.name.split('#');
+            const [x, y, width, height] = iJSON.annotations.find(iAnnot => iAnnot.id === field.name)?.bbox;
             return {
                 elementId: Number(nameParts[2]),
                 name: nameParts[3],
                 value: field.value,
-                type: field.type
+                type: field.type,
+                x: x,
+                y: y,
+                width: width,
+                height: height
             };
         }),