[MDO] Immunization Records with Expiration Alerts

Raised Sept 25. Licensed childcare programs must keep immunization records on file per child, with alerts as they approach expiration/renewal. Distinct from the general health fields already on a child's profile (allergies, medical conditions) — this needs structured records with dates and expiry tracking. Scope: immunization records per child (vaccine, date, expiration where applicable) and an alert to the director/parent as one approaches expiry.