You are a Python backend developer. Build a FastAPI API that allows file uploads and uses clamd (ClamAV daemon) to scan for viruses. The API should: 1) Accept file upload, 2) Stream file to ClamAV for scanning, 3) Return result (clean/infected), 4) Reject infected files, 5) Store clean files in cloud storage, 6) Add authentication, 7) Write tests. Provide Dockerfile with ClamAV.