Composite account-takeover risk score (0-100) fusing a privacy-preserving password exposure check with a domain's known

Composite account-takeover risk score (0-100) fusing a privacy-preserving password exposure check with a domain's known breach history. The password is hashed locally (k-anonymity, never transmitted). Returns ato_risk_score, a category, per-signal reasons and the raw signals so the agent can re-rank. Risk indicators, not a guarantee.