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/vendor/setasign/fpdf/tutorial/countries.txt

@@ -0,0 +1,15 @@
+Austria;Vienna;83859;8075
+Belgium;Brussels;30518;10192
+Denmark;Copenhagen;43094;5295
+Finland;Helsinki;304529;5147
+France;Paris;543965;58728
+Germany;Berlin;357022;82057
+Greece;Athens;131625;10511
+Ireland;Dublin;70723;3694
+Italy;Roma;301316;57563
+Luxembourg;Luxembourg;2586;424
+Netherlands;Amsterdam;41526;15654
+Portugal;Lisbon;91906;9957
+Spain;Madrid;504790;39348
+Sweden;Stockholm;410934;8839
+United Kingdom;London;243820;58862