Adds nine cases against useFormDraft's submitter surface. The S3a PR 1
smoke test found that submitter name/email were never sent to the
backend — a proper test would have caught that.
Covers: initial empty state, setter dirty-tracking flowing into the PUT
body, both name and email in the POST /submit body, the
MISSING_SUBMITTER guard when either field is empty (no endpoint call),
sessionStorage resume populating state and the initial start POST, and
session cleanup after successful submit.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bert.hausmans
71be107c54