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/composer.json

@@ -0,0 +1,18 @@
+{
+    "name": "andig/videodb",
+    "type": "project",
+    "require": {
+        "guzzlehttp/guzzle": "^6.3",
+        "smarty/smarty": "^3.1",
+        "pear/ole": "^v1.0.0RC8",
+        "pear/spreadsheet_excel_writer": "^v0.9.7",
+        "setasign/fpdf": "^1.8",
+        "james-heinrich/phpthumb": "v1.7.19"
+    },
+    "authors": [
+        {
+            "name": "andig",
+            "email": "cpuidle@gmx.de"
+        }
+    ]
+}