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/contrib/setOwner.sql

@@ -0,0 +1,7 @@
+# This SQL statement changes the owner of all unowned movies be sure to change
+# NEWOWNER to the name of the user who should own the movies.
+
+UPDATE videodata
+   SET owner = 'NEWOWNER'
+ WHERE owner IS NULL
+    OR owner = '';