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/guzzlehttp/promises/composer.json

@@ -0,0 +1,58 @@
+{
+    "name": "guzzlehttp/promises",
+    "description": "Guzzle promises library",
+    "keywords": ["promise"],
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Graham Campbell",
+            "email": "hello@gjcampbell.co.uk",
+            "homepage": "https://github.com/GrahamCampbell"
+        },
+        {
+            "name": "Michael Dowling",
+            "email": "mtdowling@gmail.com",
+            "homepage": "https://github.com/mtdowling"
+        },
+        {
+            "name": "Tobias Nyholm",
+            "email": "tobias.nyholm@gmail.com",
+            "homepage": "https://github.com/Nyholm"
+        },
+        {
+            "name": "Tobias Schultze",
+            "email": "webmaster@tubo-world.de",
+            "homepage": "https://github.com/Tobion"
+        }
+    ],
+    "require": {
+        "php": ">=5.5"
+    },
+    "require-dev": {
+        "symfony/phpunit-bridge": "^4.4 || ^5.1"
+    },
+    "autoload": {
+        "psr-4": {
+            "GuzzleHttp\\Promise\\": "src/"
+        },
+        "files": ["src/functions_include.php"]
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "GuzzleHttp\\Promise\\Tests\\": "tests/"
+        }
+    },
+    "scripts": {
+        "test": "vendor/bin/simple-phpunit",
+        "test-ci": "vendor/bin/simple-phpunit --coverage-text"
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "1.5-dev"
+        }
+    },
+    "config": {
+        "preferred-install": "dist",
+        "sort-packages": true
+    }
+}