fix(health): optimize backend health checks for Hugging Face multi-tenant environment

fix: return structured JSON on database and unhandled exceptions in middleware

sync: sync backend code, models, schemas, and API routers to Hugging Face Space cleanly

fix(auth): avoid email validator dependency

feat(auth): add google sign-in

fix: slim space startup and runtime payload

fix: fail fast on hosted postgres startup

fix: deploy stable sklearn screening model

chore: slim space runtime dependencies

fix: add xgboost to space runtime

fix: fall back to shipped archive model in space

fix: sync current backend runtime to space

Update backend for account workflows and calibration

Switch email delivery to Gmail API

Switch email delivery to SendGrid API

Deploy hosted email delivery backend

Deploy hosted email delivery backend

Deploy hosted email delivery backend

Deploy hosted email delivery backend

Fix Space routing and root docs redirect

Deploy AnemiaLens backend to Hugging Face Space