test(e2e): update Playwright screenshots and add better tests and assertions for area calculations (#6022)

* Add (better) assertions for area calculation fixes.
* Add SVG and measurement side panel area for freehand ROI test.
* Add Playwright viewport screenshot scope migration guide.
* Update cornerstonjs dependencies to 4.22.8. Ensure all versions of @babel/preset-env are 7.29.5.

---------

Co-authored-by: Ghadeer Albattarni <165973963+GhadeerAlbattarni@users.noreply.github.com>

tests/Spline.spec.ts

@@ -1,4 +1,11 @@
-import { checkForScreenshot, screenShotPaths, test, visitStudy, expect } from './utils';
+import {
+  checkForScreenshot,
+  expect,
+  getAnnotationStats,
+  screenShotPaths,
+  test,
+  visitStudy,
+} from './utils';
 import { press } from './utils/keyboardUtils';
 
 test.beforeEach(async ({ page }) => {
@@ -24,7 +31,22 @@ test('should display the spline tool', async ({
     { x: 383, y: 461 },
   ]);
   await DOMOverlayPageObject.viewport.measurementTracking.confirm.click();
-  await checkForScreenshot(page, page, screenShotPaths.spline.splineDisplayedCorrectly);
+  await checkForScreenshot(
+    page,
+    viewportPageObject.grid,
+    screenShotPaths.spline.splineDisplayedCorrectly
+  );
+
+  const splines = await getAnnotationStats(page, { toolName: 'SplineROI' });
+  expect(splines.length).toBeGreaterThan(0);
+
+  const stats = splines[0].firstTargetStats!;
+  expect(stats.areaUnit).toBe('mm²');
+  expect(Math.round(stats.area as number)).toBe(38811);
+
+  const lines = activeViewport.getSvgAnnotationStatTextLines(splines[0].annotationUID);
+  await expect(lines).toHaveCount(1);
+  await expect(lines.nth(0)).toHaveText('Area: 38811 mm²');
 });
 
 test('should restore viewport interactivity after deleting an in-progress Spline annotation via context menu', async ({