- backend: _ack_summary_for_claims helper attaches claim_acks payload
to inbox rejected-lane rows (3 tests)
- frontend: InboxRow renders newest 3 AK2 chips + '+N more' overflow
under the rejection reason, with '999 not linked' marker when an
ack couldn't be linked to a claim
- frontend: per-row Resubmit button downloads a single corrected 837
via api.serializeClaim837 (no bulk modal, no zip — one click, one
.x12 file)
- frontend: 2 new tests for the chip rendering and the per-row
download flow