fix(frontend): replay row-flash on every refetch via dataUpdatedAt key

The previous static key={c.id} let React reuse the same <TableRow>
element across refetches, so animate-row-flash only played on
initial mount and on the first render of a brand-new claim_id.
Updated rows whose claim_id was unchanged never re-flashed.

Re-keying on `${c.id}-${dataUpdatedAt}` re-mounts the row on
every refetch (initial load, filter change, parse invalidation),
so the 1.2s accent-tint flash replays each time.

Also: README's 'Frontend unit tests (when added)' is stale — npm
test now exists and runs 3 passing tests.

hooks: add dataUpdatedAt: 0 to the !isConfigured fallback return
so the pages type-check.

src/pages/Remittances.tsx

@@ -30,7 +30,7 @@ export function Remittances() {
   const [page, setPage] = useState(1);
   const [status, setStatus] = useState<RemittanceStatus | null>(null);
 
-  const { data, isLoading, isError, error, refetch } = useRemittances({
+  const { data, isLoading, isError, error, refetch, dataUpdatedAt } = useRemittances({
     sort: "receivedDate",
     order: "desc",
     limit: PAGE_SIZE,
@@ -128,7 +128,7 @@ export function Remittances() {
               </TableHeader>
               <TableBody>
                 {items.map((r) => (
-                  <TableRow key={r.id} className={cn("animate-row-flash")}>
+                  <TableRow key={`${r.id}-${dataUpdatedAt}`} className={cn("animate-row-flash")}>
                     <TableCell className="display num text-[13px]">{r.id}</TableCell>
                     <TableCell className="display num text-[13px] text-muted-foreground">
                       {r.claimId}