Project upload moderation system

Implement automated filtering for uploaded projects to prevent inappropriate content (e.g., pornographic or unrelated files).
The system should:

Automatically scan uploaded files using an AI or keyword/image detection service.
Reject flagged uploads with an error message (“File content violates upload policy”).
Tag approved uploads for lecturer review.
Allow lecturers to download and review student projects from their dashboard.

Backend: File scanning, filtering logic, lecturer access permissions, and secure download endpoints.

Frontend: Display upload status, error messages, and lecturer review access interface.

The issue describes a full moderation system. Start by examining the existing project upload flow in the backend code to understand where file scanning would be integrated. Research AI or detection services for content filtering. The frontend will need new components for upload status and a lecturer review interface. 'Done' means automated scanning, rejection messages, tagging for review, and secure lecturer download endpoints are all implemented.

Written by the indexing model from the issue text.