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/templates/default/contrib.tpl

@@ -0,0 +1,28 @@
+{*
+  Index of the contrib content
+  $Id: contrib.tpl,v 2.2 2005/05/26 07:35:45 andig2 Exp $
+*}
+
+<table width="100%" class="tablelist" cellspacing="0" cellpadding="0">
+<tr><td colspab="3" height="20px">&nbsp;</td></tr>
+{counter start=0 print=false name=contentcount}
+{foreach item=file from=$files}
+    {cycle values="even,odd" assign=CLASS print=false}
+    <tr class="{$CLASS}">
+
+    <td width="10%">
+    <td width="80%" align="left">
+        <table>
+        <tr>
+            <td>
+                    <a href="{$file[0]}">{$file[1]}</a>
+            </td>
+        </tr>
+        </table>
+    </td>
+    <td width="10%">
+    {counter assign=count name=contentcount}
+    </tr>
+{/foreach}
+<tr><td colspab="3" height="20px">&nbsp;</td></tr>
+</table>