usage tests: TestReasoningReplyTimedByItsAnswer's timeline rows are made now, as LedgerSeries buckets today by the clock

The test gave LedgerSeries records dated 2026-10-06 14:30 UTC while
LedgerSeries reads today from time.Now(), so it passed only on 2026-10-06
and has failed on every machine since ("part: {Calls:0 ...}" just after
midnight CST on 10-07). The summary and row checks keep the fixed date;
the rows given to LedgerSeries take the clock's. go test -race
./internal/usage passes; gofmt and vet are clean.

internal/usage/usage_test.go

@@ -235,6 +235,9 @@ func TestReasoningReplyTimedByItsAnswer(t *testing.T) {
 	var lr []Row
 	for _, r := range recs {
 		rows.addRow(Row{Record: r})
+		// LedgerSeries buckets today by the clock, so the timeline's rows
+		// are made now
+		r.Time = time.Now()
 		lr = append(lr, Row{Record: r})
 	}
 	if rows.Timed != 6 || rows.DecodeMs != ms || rows.DecodeOut != out {