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/xml.core.php

@@ -0,0 +1,107 @@
+<?php
+/**
+ * XML support functions
+ *
+ * @package Core
+ * @author  Andreas Götz    <cpuidle@gmx.de>
+ * @version $Id: xml.core.php,v 1.8 2013/04/26 15:09:35 andig2 Exp $
+ */
+ 
+/**
+ * See http://feedvalidator.org/docs/error/InvalidRFC2822Date.html
+ */
+$GLOBALS['rss_timestamp_format']    = 'D, j M Y H:i:s O';
+
+/**
+ * Encodes HTML entities into XML character entities
+ * this avoids problems with unknown entities in XML
+ *
+ * @param   string  $string HTML string to encode
+ * @return  string          encoded string containing XML character entities  
+ */
+function encode_character_entities($string)
+{
+    return strtr($string, get_html_translation_table(HTML_SPECIALCHARS));
+#   return strtr($string, array_flip(get_html_translation_table(HTML_SPECIALCHARS)));
+}
+
+/**
+ * Create an XML tag
+ *
+ * @param   string  $tag    XML tag name
+ * @param   string  $value  value for XML tag
+ * @param   boolean $encode require encoding of tag value
+ * @return  string          XML tag
+ */
+function createTag($tag, $value, $encode = true)
+{
+    if ($encode) $value = encode_character_entities($value);
+    return "<$tag>".$value."</$tag>\n";
+}
+
+function createContainer($tag, $value = '')
+{
+    return createTag($tag, $value, false);
+}
+
+/**
+ * Convert MySQL Date to RSS timestamp
+ *
+ * @return string   RFC 2822 Date (http://feedvalidator.org/docs/error/InvalidRFC2822Date.html)
+ */
+function rss_timestamp($timestamp)
+{
+    global $rss_timestamp_format;
+
+    // Lets sort this nasty timestamp nonsense out ;D
+    $y          = substr($timestamp, 0, 4);
+    $m          = substr($timestamp, 5, 2);
+    $d          = substr($timestamp, 8, 2);
+    $h          = substr($timestamp, 11, 2);
+    $min        = substr($timestamp, 14, 2);
+    $s          = substr($timestamp, 17, 2);
+
+    $timestamp  = mktime($h, $min, $s, $m, $d, $y);
+
+    return date($rss_timestamp_format, $timestamp);
+}
+
+/**
+ * Load XML into SimpleXML object
+ * Fixes potential encoding issue
+ */
+function load_xml($data)
+{
+    $xml = simplexml_load_string($data, $root = 'SimpleXMLElement', LIBXML_NOCDATA);
+
+    // character encoding warning- hack
+    if ($xml === false) 
+    {
+        $error = error_get_last();
+#       dump($error);
+
+        // this is nasty- sometimes simplexml_load_string fails but doesn't raise an error
+        if (preg_match('/simplexml_load_string/i', $error['message']))
+        {
+            $xml = simplexml_load_string(utf8_encode($data), $root, LIBXML_NOCDATA);
+        }
+    }
+    
+    return $xml;
+}
+
+/**
+ * Concatenate string-converted xml entities
+ */
+function xml_join($items, $str = "\n")
+{
+    foreach ($items as $item)
+    {
+        if ($data) $data .= $str;
+        $data .= (string) $item;
+    }
+
+    return $data;
+}
+
+?>