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/profile.tpl

@@ -0,0 +1,18 @@
+{*
+  The configuration template
+  $Id: profile.tpl,v 2.2 2004/06/09 16:13:05 agohr Exp $
+*}
+
+<form method="post" action="profile.php">
+<input type="hidden" name="save" value="1" />
+<table width="100%" class="tableborder">
+  {include file="options.tpl"}
+</table>
+
+<br />
+<div align="center">
+  <input type="submit" value="{$lang.save}" accesskey="s" />
+</div>
+<br />
+
+</form>