Each target's row shows its result as soon as its check ends (closes #91)

tick drew no row until the round's slowest check ended, up to 24
seconds at a 30-second interval since checks time out at 80% of it.
Each check now pushes its sample and redraws its row as it ends;
sorting, the summary, the health box and offline detection still run
once, after the last check. A check that ends while paused or after its
round is given up draws nothing, and the first round is still discarded
as a whole. The row is looked up when the check ends, as a pin click
can re-sort the rows mid-round.

The new unit test runs tick on the mocked clock against a stand-in
page.

Model: opus-5-5

TODO.md

@@ -23,6 +23,12 @@ latest run passes.
 
 # Completed Steps
 
+- 2026-10-03: each target's row shows its result as soon as its check ends
+  (issue #91), where every row waited for the round's slowest check, up to 24
+  seconds at a 30-second interval. Sorting, the summary, the health box and
+  offline detection still run once, when the round's last check ends. A check
+  that ends after the user pauses or after its round is given up shows nothing,
+  and the first round is still discarded as a whole
 - 2026-10-03: the Go tests run with the race detector and coverage (issue #88):
   `backend/script/test` runs `go test -timeout 30s -race -cover ./...` and, if
   that fails, runs it again with `-v` and fails. Go's `-timeout` bounds the