feat: add videodb media index with Docker stack

- Add videodb PHP/MySQL media collection manager (Blu-ray, DVD, CD)
- Dockerfile: PHP 8.1 + Apache with GD/mysqli/exif extensions
- docker-compose.yml: app on port 6761 + MySQL 8.0 with health checks
- docker-entrypoint.sh: auto-generates config.inc.php from env vars,
  waits for MySQL, initializes DB schema idempotently
- init-db.php: CLI schema installer using app's own prefix_query() logic
- Persistent volumes for DB, cache, and cover images

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

videodb/core/security.php

@@ -0,0 +1,59 @@
+<?php
+/**
+ * Security functions
+ *
+ * @package Core
+ * @author  Andreas Goetz   <cpuidle@gmx.de>
+ * @author  tREXX           <www.trexx.ch>
+ * @version $Id: security.php,v 1.2 2008/01/05 13:50:58 andig2 Exp $
+ */
+
+/**
+ * Allow these tags
+ */
+$allowedTags = '<h1><h2><h3><h4><b><strong><i><a><ol><ul><li><pre><hr><blockquote>';
+
+/**
+ * Disallow these attributes/prefix within a tag
+ */
+$stripAttrib = 'javascript:|onclick|ondblclick|onmousedown|onmouseup|onmouseover|'.
+               'onmousemove|onmouseout|onkeypress|onkeydown|onkeyup';
+
+/**
+ * @return string
+ * @param string
+ * @desc Strip forbidden attributes from a tag
+ */
+function removeEvilAttributes($tagSource)
+{
+    global $stripAttrib;
+    return stripslashes(preg_replace("/$stripAttrib/i", 'forbidden', $tagSource));
+}
+
+/**
+ * @return string
+ * @param string
+ * @desc Strip forbidden attributes from an array of matches for an expression like (<)(.*?)(>)
+ */
+function _callbackRemoveEvilAttributes($matches)
+{
+    return $matches[1] . removeEvilAttributes($matches[2]) . $matches[3];
+}
+
+/**
+ * @return string
+ * @param string
+ * @desc Strip forbidden tags and delegate tag-source check to removeEvilAttributes()
+ */
+function removeEvilTags($source)
+{
+    global $allowedTags;
+    if (!is_null($source))
+    {    
+        $source = strip_tags($source, $allowedTags);
+        return preg_replace_callback('/(<)(.*?)(>)/i', "_callbackRemoveEvilAttributes", $source);
+    }
+    return $source;
+}
+
+?>