fix(e2e): wait for swapped senderId in URL instead of any senderId

waitForURL(/senderId=/) resolved immediately because the URL already
contained senderId= before the swap navigation. Use a predicate that
waits for the specific swapped ID value.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/e2e/persons.spec.ts

@@ -259,7 +259,10 @@ test.describe('Conversations — enhancements', () => {
 		const originalReceiverId = url.searchParams.get('receiverId')!;
 
 		await page.getByTestId('conv-swap-btn').click();
-		await page.waitForURL(/senderId=/);
+		// Wait for the URL to reflect the swapped IDs (not just any URL with senderId=)
+		await page.waitForURL(
+			(url) => new URL(url).searchParams.get('senderId') === originalReceiverId
+		);
 
 		const swappedUrl = new URL(page.url());
 		expect(swappedUrl.searchParams.get('senderId')).toBe(originalReceiverId);