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/README.md

@@ -0,0 +1,34 @@
+videoDB
+=======
+
+VideoDB is a PHP-based web application to manage a personal video collection. Multiple video types are supported, ranging from VHS tapes and DVDs to Blu-ray discs and DivX files on hard-disc. Even video games are supported.
+
+Introduction
+------------
+
+### Browse
+
+You can use videoDB to manage your video and CD collection, be it DVD, BluRay or plain Files:
+
+![Browse Movies](https://raw.github.com/andig/videodb/master/doc/screenshots/0.png)
+
+### View
+
+![View Details](https://raw.github.com/andig/videodb/master/doc/screenshots/1.png)
+
+### Edit
+All data is editable in nice layed out forms:
+
+![Edit](https://raw.github.com/andig/videodb/master/doc/screenshots/2.png)
+
+### IMDB
+
+New movies are easily added directly from IMDB or other sources:
+
+![IMDB](https://raw.github.com/andig/videodb/master/doc/screenshots/3.png)
+
+### Config
+
+videoDB is also highly customizable- almost every aspect can be changed from template selection to detailed customization:
+
+![Config](https://raw.github.com/andig/videodb/master/doc/screenshots/4.png)