feat: validate on submit only and re-announce errors to screen readers
Linked to https://gitlab.uncinc.nl/orgs/uncinc/uncinc-frontend/-/merge_requests/325
Disables Formik's validateOnChange and validateOnBlur so validation only runs on submit. Fixes screen readers not re-announcing repeated validation errors by clearing touched state and yielding before re-validating, forcing the aria-live region to pick up the re-appearing messages.
Co-Authored-By: Claude Sonnet 4.6 noreply@anthropic.com
Edited by Owen Byrne