fix(annotations): correct signature frame mapping by filtering by pageIndex

- Updated `mapSignature` to filter signature annotations by `pageIndex` when finding nearest elements.
- Ensures correct association of frames and signature data for each page.
- Prevents errors caused by cross-page annotation references.

EnvelopeGenerator.Web/wwwroot/js/util.js

@@ -14,7 +14,7 @@ function detailedCurrentDate() {
     }).format();
 }
 
-function findNearest(origin, getX, getY, ...dests) { 
+function findNearest(origin, getX, getY, dests) { 
     const distanceToOrigin = (point) => Math.sqrt((getX(origin) - getX(point))**2 + (getY(origin) - getY(point))**2);
     return dests.reduce(
         (nearest, dest) => {