Normalize paths in the signature parity check

The manifest stores forward-slash paths; on Windows the
realpath()-derived location uses backslashes and every shadowed class
was reported as living in the wrong file.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013j6ePxd1BobZkr8YVLnNet
(cherry picked from commit 3656e5f)

Author: ondrejmirtes

turbo-ext/tests/signature-parity.php

@@ -73,7 +73,8 @@ function visibility(ReflectionMethod $m): string
 
 	// the manifest must point at the file the class actually lives in
 	// (bin/side-by-side.php parses that file's source as the PHP side)
-	$actualFile = substr(realpath($twin->getFileName()), strlen(realpath($root)) + 1);
+	// normalized to forward slashes: the manifest stores portable paths
+	$actualFile = str_replace(DIRECTORY_SEPARATOR, '/', substr(realpath($twin->getFileName()), strlen(realpath($root)) + 1));
 	if ($actualFile !== $entry['php']) {
 		$problems[] = sprintf('lives in %s, but the manifest says %s — regenerate with bin/side-by-side.php --update-manifest', $actualFile, $entry['php']);
 	}