Bump FileTypeMapper cache key to discard entries poisoned by comment-dropping parses

A run with the turbo comment-loss bug (phpstan/phpstan#15037) cached
PHPDoc-less name-scope maps under ftm- keys. The entries validate only by
file content hashes and the phpdoc-parser version, so an upgrade to the
fixed extension keeps trusting them — analysis stays broken (missing
generics, mass false positives) until the tmpDir is wiped by hand, and
clear-result-cache does not help. Rotate the variable cache key to v6 so
every installation rebuilds the maps once.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EpvCn4kVHSaS5aaiaaRhEm

Author: ondrejmirtes

src/Type/FileTypeMapper.php

@@ -347,7 +347,11 @@ private function getNameScopeMap(string $fileName): array
 		}
 
 		$cacheKey = sprintf('ftm-%s', $fileName);
-		$variableCacheKey = sprintf('v5-%s', ComposerHelper::getPhpDocParserVersion());
+		// v6: v5 entries may be poisoned by the turbo comment-loss bug
+		// (https://github.com/phpstan/phpstan/issues/15037) - a parse that
+		// silently dropped every comment cached PHPDoc-less name-scope maps,
+		// and the content hashes cannot tell them apart from real ones.
+		$variableCacheKey = sprintf('v6-%s', ComposerHelper::getPhpDocParserVersion());
 		$cached = $this->loadCachedPhpDocNodeMap($cacheKey, $variableCacheKey);
 		if ($cached === null) {
 			[$nameScopeMap, $files] = $this->createPhpDocNodeMap($fileName, null, null, [], $fileName);