Enhance Docker and backend configurations for improved deployment

- Updated docker-compose.yml to include environment variable support for services, enhancing flexibility in configuration.
- Refactored Dockerfile to utilize build arguments for VITE environment variables, allowing for better customization during builds.
- Improved Nginx configuration to handle larger video uploads by increasing client_max_body_size to 5GB.
- Enhanced backend Dockerfile to include wget for health checks and improved startup logging for database migrations.
- Added validation for critical environment variables in the backend to ensure necessary configurations are present before application startup.
- Updated content streaming logic to support direct HLS URL construction, improving streaming reliability and user experience.
- Refactored various components and services to streamline access checks and improve error handling during content playback.

nginx.conf

@@ -42,8 +42,8 @@ server {
         proxy_read_timeout 300s;
         proxy_send_timeout 300s;
 
-        # Handle large uploads
-        client_max_body_size 100m;
+        # Handle large video uploads (up to 5GB)
+        client_max_body_size 5g;
     }
 
     # ── MinIO storage proxy (public bucket) ────────────────────