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/Dockerfile

@@ -0,0 +1,51 @@
+FROM php:8.1-apache
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y \
+    libpng-dev \
+    libjpeg-dev \
+    libfreetype6-dev \
+    default-mysql-client \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install PHP extensions needed by videoDB
+RUN docker-php-ext-configure gd --with-freetype --with-jpeg \
+    && docker-php-ext-install -j$(nproc) \
+        gd \
+        mysqli \
+        exif \
+        mbstring
+
+# Enable Apache mod_rewrite for .htaccess
+RUN a2enmod rewrite
+
+# Allow .htaccess overrides in document root
+RUN sed -i '/<Directory \/var\/www\/>/,/<\/Directory>/ s/AllowOverride None/AllowOverride All/' /etc/apache2/apache2.conf
+
+# Set working directory to document root
+WORKDIR /var/www/html
+
+# Copy application (including vendor which is committed to the repo)
+COPY . .
+
+# Create cache directories and set permissions
+RUN mkdir -p \
+        cache/smarty \
+        cache/imdb \
+        cache/img \
+        cache/thumbs \
+        cache/javascript \
+        cache/local \
+    && chown -R www-data:www-data \
+        cache \
+        images
+
+# Copy entrypoint and db-init scripts
+COPY docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh
+COPY init-db.php /usr/local/bin/init-db.php
+RUN chmod +x /usr/local/bin/docker-entrypoint.sh
+
+EXPOSE 80
+
+ENTRYPOINT ["docker-entrypoint.sh"]
+CMD ["apache2-foreground"]