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/james-heinrich/phpthumb/licenses/license.ptcl.txt

@@ -0,0 +1,27 @@
+                 phpThumb() Commercial License
+                 =============================
+
+phpThumb() is licensed under the "GNU Public License" (GPL) and/or the
+"phpThumb() Commercial License" (pTCL). This document describes the pTCL.
+
+---------------------------------------------------------------------
+
+The license is non-exclusively granted to a single person or company,
+per payment of the license fee, for the lifetime of that person or
+company. The license is non-transferrable.
+
+The pTCL grants the licensee the right to use phpThumb() in commercial
+closed-source projects. Modifications may be made to phpThumb() with no
+obligation to release the modified source code. phpThumb() (or pieces
+thereof) may be included in any number of projects authored (in whole
+or in part) by the licensee.
+
+The licensee may use any version of phpThumb(), past, present or future,
+as is most convenient. This license does not entitle the licensee to
+receive any technical support, updates or bugfixes, except as such are
+made publicly available to all phpThumb() users.
+
+The licensee may not sub-license phpThumb() itself, meaning that any
+commercially released product containing all or parts of phpThumb() must
+have added functionality beyond what is available in phpThumb();
+phpThumb() itself may not be re-licensed by the licensee.