Ensure OTP endpoint reports real delivery status

Improve OTP delivery resilience and non-blocking reset flow

Add Resend fallback and email provider config

fix(auth+email): prevent SMTP blocking timeout and harden Google OAuth redirect

refactor(auth): suppress legacy hash noise and keep one-time migration

fix(auth): migrate legacy plaintext password on successful login

fix(auth): handle unknown password hash without 500

fix(db): normalize postgresql scheme to asyncpg

fix(prod): robust DB SSL modes and cert chain handling

fix(db): sanitize DATABASE_URL and harden asyncpg engine config

Sync deploy essentials: backend, models, docker config

initial commit