Design a healthcare appointment system with HIPAA compliance.

patients(id UUID PK, name_encrypted BYTEA, ssn_encrypted BYTEA, dob DATE, created_at) — encrypt PII at application level doctors(id, license_number UNIQUE, specialty, department_id FK) appointments(id, patient_id FK, doctor_id FK, scheduled_at TIMESTAMPTZ, status, notes_encrypted BYTEA) audit_log: every SELECT/INSERT/UPDATE/DELETE logged with user_id, patient_id, timestamp, action Row-Level Securi