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/elegant/help.tpl

@@ -0,0 +1,14 @@
+{*
+
+  The help template
+
+  $Id: help.tpl,v 1.2 2005/05/22 10:29:57 andig2 Exp $
+
+*}
+
+
+
+<!-- {$smarty.template} -->
+
+
+