The Acks page mounts two streams (useTailStream("acks") and
useTailStream("ta1_acks")) — the dispatcher now routes their item
events into the matching store slices (addAck / addTa1Ack) the same
way the claims / remittances / activity cases already do.
Two new tests assert that an acks item lands in the acks slice (not
in claims) and a ta1_acks item lands in the ta1Acks slice (not in
acks) — i.e. the routing is exclusive, so a payload keyed by id 7
won't bleed across the two ack tables.