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/composer.json

@@ -0,0 +1,36 @@
+{
+    "name": "james-heinrich/phpthumb",
+    "description": "The PHP thumbnail generator",
+    "type": "library",
+    "license": ["GPL-1.0-or-later", "LGPL-3.0-only", "MPL-2.0"],
+	"authors": [
+        {
+            "name": "James Heinrich",
+            "email": "info@silisoftware.com",
+            "homepage": "http://www.silisoftware.com/",
+            "role": "Developer"
+        }
+    ],
+    "keywords": ["thumbnail", "thumb", "GD", "ImageMagick", "image", "magic"],
+    "homepage": "http://phpthumb.sourceforge.net/",
+    "require": {
+        "php": ">=5.3.0"
+    },
+    "scripts": {
+        "post-autoload-dump": [
+            "composer run copy-config",
+            "composer run hsp-generate"
+        ],
+        "copy-config": "php -r \"copy('phpThumb.config.php.default', 'phpThumb.config.php');\"",
+        "hsp-generate": "php -r \"$cf=file_get_contents('phpThumb.config.php');$cf=str_replace('__HSP_KEY__', base64_encode(bin2hex(random_bytes(22))), $cf);file_put_contents('phpThumb.config.php', $cf);\""
+    },
+    "suggest": {
+        "ext-gd": "PHP GD library",
+        "ext-imagick": "PHP ImageMagick"
+    },
+    "autoload": {
+        "files": [
+            "phpthumb.class.php"
+        ]
+    }
+}