feat: ICO and web manifest files can be uploaded to fileadmin

TYPO3 13 only accepts uploads whose extension is in textfile_ext,
mediafile_ext or miscfile_ext (security.system.enforceAllowedFileExtensions),
so the favicon.ico and site.webmanifest of a realfavicongenerator set were
rejected ("Resource consistency check failed"). Both are appended to
miscfile_ext in additional.php, which is deployed with the code;
settings.php, which production leads, stays untouched.

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

config/system/additional.php

@@ -94,6 +94,10 @@ $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['rootline']
 ];
 unset($redisOptions);
 
+// Favicon sets from realfavicongenerator.net (fileadmin/user_upload/favicon/<site>/) contain an ICO
+// and a web manifest, which TYPO3 13 rejects on upload unless an extension list allows them
+$GLOBALS['TYPO3_CONF_VARS']['SYS']['miscfile_ext'] .= ',ico,webmanifest';
+
 // Deployer creates an empty secrets.php if none exists yet: only an array counts
 $secrets = is_file(__DIR__ . '/secrets.php') ? require __DIR__ . '/secrets.php' : null;
 if (is_array($secrets)) {