Move ai-stack and paintplus vendored source under vendor/

Matches the existing vendor/easy-asterisk convention (used by
services/asterisk.sh) instead of two one-off top-level directories that
cluttered the repo root and didn't look like anything else next to
setup.sh, lib/, services/, extras/. Only the two services' own SRC_DIR
path resolution and header comments needed updating — nothing else in
the repo referenced the old ./ai-stack / ./paintplus paths.

Also documents vendor/ in README.md's Layout section.

vendor/paintplus/frontend/tools/translator/config.php

@@ -0,0 +1,32 @@
+<?php
+
+$SOURCE_DIRS = [
+	__DIR__ . '/../../index.html',
+	__DIR__ . '/../../src/js/core/',
+	__DIR__ . '/../../src/js/modules/',
+	__DIR__ . '/../../src/js/tools/',
+	__DIR__ . '/../../src/js/config.js',
+	__DIR__ . '/../../src/js/config-menu.js',
+	__DIR__ . '/../../src/js/main.js',
+	__DIR__ . '/../../src/js/libs/popup.js',
+];
+
+$LANGUAGES = [
+	'ar',
+	'de',
+	'es',
+	'fr',
+	'it',
+	'ja',
+	'ko',
+	'lt',
+	'pt',
+	'ru',
+	'tr',
+	'zh',
+	'el',
+	'nl',
+];
+
+$LANG_DIR = __DIR__ . '/../../src/js/languages/';
+$LANG_DIR_EMPTY = __DIR__ . '/../../src/js/languages/empty.json'; //leave empty to skip