f1bee546f6
The Acks page needs the same live-tail triplet (useTailStream +
useMergedTail + TailStatusPill) that Claims/Remittances/Activity
already use. The first step is widening the TailResource union so
streamTail("acks") and streamTail("ta1_acks") are valid and the
URL falls out as /api/acks/stream and /api/ta1-acks/stream.
Two new tests assert the URL targets the new backend endpoints.