feat: EXT:staticfilecache serves cached pages without PHP again, as on TYPO3 10

Every page view goes through TYPO3 13 since the switch; staticfilecache
15.2 writes a gzip copy of each cacheable page, and the TYPO3 10 rewrite
rules in public/.htaccess let Apache deliver it directly (GET, no query
string, no backend login). Pages answer in about 2 ms instead of
0.5-4 s; static and dynamic output are identical for a sample of 22
sitemap URLs.

A flush of the pages cache group (travel data and snow report imports,
"clear frontend caches", deploys) removes the files; a page's own cache
lifetime still applies through the generated per-page .htaccess.

X-SFC-Tags is not passed on: with every record of a page as a tag it
reaches 100+ KB, more than Apache accepts from PHP-FPM, and it would
expose internal record ids. Debug headers stay off for the same reason.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

composer.json

@@ -20,6 +20,7 @@
 		"ep/ep-theme": "@dev",
 		"fluidtypo3/vhs": "^8.0",
 		"georgringer/news": "^14.1",
+		"lochmueller/staticfilecache": "^15.2",
 		"ssch/typo3-encore": "^7.0",
 		"typo3/cms-backend": "^13.4",
 		"typo3/cms-belog": "^13.4",