feat: add S3 env config, bucket and multipart DB schema

.env.example

@@ -8,4 +8,9 @@ NODE_ENV=production
 LOG_LEVEL=info
 RATE_LIMIT_WINDOW_MS=60000
 RATE_LIMIT_MAX_REQUESTS=30
-# TRUST_PROXY=true  # Uncomment when behind reverse proxy (Traefik, Nginx) for correct client IP detection
+# TRUST_PROXY=true  # Uncomment when behind reverse proxy (Traefik, Nginx) for correct client IP detection
+
+# S3-compatible API credentials
+# S3_ACCESS_KEY=teleuploader-admin
+# S3_SECRET_KEY=your-secret-key-here
+# S3_DEFAULT_REGION=us-east-1