feat: FastAPI backend + full deployment stack (Railway + Vercel)
- FastAPI backend: /health, /api/upload (CSV parse + score), /api/export (work queue CSV)
- CSV normalizer: tolerates 10+ header aliases per field, 8 date formats, all 5 devices, all major payers
- Python coverage_calculator wired as the authoritative scoring engine
- Frontend: backend-first upload with local fallback, export CSV wired, J. Sullivan placeholder removed
- Dockerfile + railway.toml for Railway deploy
- vercel.json for static frontend deploy
- Railway MCP installed for future sessions
Backend live: https://signal-api-production-91c2.up.railway.app
Frontend live: https://signal-ui-xi.vercel.app
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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