remove existing folders fonts and vendor from local installations (#3805)

see discussions
[here](#3795 (comment)).

The used command should work under windows too. I'm open to better
solutions.

Co-authored-by: Veeck <github@veeck.de>

Author: khassel

CHANGELOG.md

@@ -32,7 +32,7 @@ planned for 2025-07-01
 - [workflow] Replace Node.js version v23 with v24 (#3770)
 - [refactor] Replace deprecated constants `fs.F_OK` and `fs.R_OK` (#3789)
 - [refactor] Replace `ansis` with built-in function `util.styleText` (#3793)
-- [core] Integrate stuff from `vendor` and `fonts` folders into main `package.json`, simplifies install and maintaining dependencies (#3795)
+- [core] Integrate stuff from `vendor` and `fonts` folders into main `package.json`, simplifies install and maintaining dependencies (#3795, #3805)
 - [l10n] Complete translations (with the help of translation tools) (#3794)
 
 ### Fixed

package.json

@@ -32,6 +32,7 @@
 		"lint:js": "eslint --fix",
 		"lint:markdown": "markdownlint-cli2 . --fix",
 		"lint:prettier": "prettier . --write",
+		"postinstall": "git clean -df fonts vendor",
 		"prepare": "[ -f node_modules/.bin/husky ] && husky || echo no husky installed.",
 		"server": "node ./serveronly",
 		"start": "node --run start:x11",