fix(deploy): enforce memory-safe spatial-FFT deepfake detector in containers to prevent 512MB OOM crash

fix(deploy): pre-cache lightweight buffalo_s model for Render free tier memory limits and improve UI fetch error handling

chore(docker): suppress pip root user warning during container build

feat(deploy): support cloud dynamic PORT binding in Dockerfile and app.py

ci: add GitHub Actions workflow, Docker containerization, and social filter unit tests