File Upload Processing Guardian

@mkelam/pdflab-file-upload-processing-guardian-skill-md

Offensive file upload and processing security and reliability enforcement. Triggered when implementing file uploads, reviewing Multer configuration, debugging upload failures, validating file types, or optimizing storage. Scans for security vulnerabilities, file size exploits, MIME type spoofing, path traversal, and storage efficiency issues. Produces auto-scan reports with security hardening recommendations.