test: Add test case for unauthenticated signer with signature file

Add test coverage for the scenario where an unauthenticated signer (e.g., via
WhatsApp) has uploaded signature elements that are stored in the folder
service but accessed from a different session context during background job
execution.

This test verifies that the system can successfully locate and use signature
files by their nodeId even when the session context differs from the upload
context.

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

tests/php/Unit/Service/SignFileServiceTest.php

@@ -1488,6 +1488,19 @@ public static function providerSetVisibleElements(): array {
 				isAuthenticatedSigner: true,
 				expectedException: LibresignException::class,
 			),
+
+			'unauthenticated signer with file in folder service (WhatsApp scenario)' => self::createScenarioSetVisibleElements(
+				signerList: [
+					['documentElementId' => $validDocumentId, 'profileNodeId' => $validProfileNodeId],
+				],
+				fileElements: [
+					['id' => $validDocumentId],
+				],
+				tempFiles: [$validProfileNodeId => $vfsPath],
+				signatureFile: [$validProfileNodeId => ['valid' => true, 'content' => 'valid content']],
+				canCreateSignature: true,
+				isAuthenticatedSigner: false,
+			),
 		];
 	}