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/ralouphie/getallheaders/README.md

@@ -0,0 +1,27 @@
+getallheaders
+=============
+
+PHP `getallheaders()` polyfill. Compatible with PHP >= 5.3.
+
+[![Build Status](https://travis-ci.org/ralouphie/getallheaders.svg?branch=master)](https://travis-ci.org/ralouphie/getallheaders)
+[![Coverage Status](https://coveralls.io/repos/ralouphie/getallheaders/badge.png?branch=master)](https://coveralls.io/r/ralouphie/getallheaders?branch=master)
+[![Latest Stable Version](https://poser.pugx.org/ralouphie/getallheaders/v/stable.png)](https://packagist.org/packages/ralouphie/getallheaders)
+[![Latest Unstable Version](https://poser.pugx.org/ralouphie/getallheaders/v/unstable.png)](https://packagist.org/packages/ralouphie/getallheaders)
+[![License](https://poser.pugx.org/ralouphie/getallheaders/license.png)](https://packagist.org/packages/ralouphie/getallheaders)
+
+
+This is a simple polyfill for [`getallheaders()`](http://www.php.net/manual/en/function.getallheaders.php).
+
+## Install
+
+For PHP version **`>= 5.6`**:
+
+```
+composer require ralouphie/getallheaders
+```
+
+For PHP version **`< 5.6`**:
+
+```
+composer require ralouphie/getallheaders "^2"
+```