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/footer.tpl

@@ -0,0 +1,26 @@
+{*
+  This is the footer which is displayed on bottom of every page
+  $Id: footer.tpl,v 2.5 2008/02/17 17:44:54 andig2 Exp $
+*}
+
+{$DEBUG}
+    <table width="100%" class="footertable">
+      <tr>
+        <td width="50">
+          <a href="#top"><img src="images/top.gif" border="0" alt="" class="toplink" /></a>
+        </td>
+        <td align="left" style="text-align:left">
+          {if !empty($loggedin)}
+            <span class="version">{$lang.loggedinas} {$loggedin}</span>
+          {/if}
+        </td>
+        <td align="right" style="text-align:right">
+          <a href="https://github.com/andig/videodb.git" class="splitbrain">v.{$version}</a>
+        </td>
+      </tr>
+    </table>
+
+    </div>
+
+  </body>
+</html>