refactor(irtt-client): move cadence into managed runner

crates/irtt-app/src/cmd/client/output.rs

@@ -207,7 +207,7 @@ enum OutputRow {
         client_send_wall: SystemTime,
         bytes: usize,
         send_call: Duration,
-        timer_error: Duration,
+        timer_error: Option<Duration>,
     },
     EchoReply(ReplyRow),
     Loss {
@@ -950,7 +950,7 @@ fn cell_for(row: &OutputRow, column: Column, context: RenderContext<'_>) -> Opti
         },
         Column::TimerErrorUs => match row {
             OutputRow::EchoSent { timer_error, .. } => {
-                Some(CellValue::Unsigned(duration_us(*timer_error)))
+                timer_error.map(|error| CellValue::Unsigned(duration_us(error)))
             }
             _ => None,
         },

crates/irtt-app/src/cmd/client/summary.rs

@@ -170,11 +170,11 @@ mod tests {
         collector.process(&ClientEvent::EchoSent {
             seq: 1,
             remote: test_remote(),
-            scheduled_at: sent_at.mono,
+            scheduled_at: Some(sent_at.mono),
             sent_at,
             bytes: 64,
             send_call: Duration::from_micros(10),
-            timer_error: Duration::from_micros(2),
+            timer_error: Some(Duration::from_micros(2)),
         });
         collector.process(&ClientEvent::EchoReply {
             seq: 1,
@@ -251,11 +251,11 @@ mod tests {
             collector.process(&ClientEvent::EchoSent {
                 seq,
                 remote: test_remote(),
-                scheduled_at: sent_at.mono,
+                scheduled_at: Some(sent_at.mono),
                 sent_at,
                 bytes: 64,
                 send_call: Duration::from_micros(send_call_us),
-                timer_error: Duration::from_micros(timer_error_us),
+                timer_error: Some(Duration::from_micros(timer_error_us)),
             });
             collector.process(&ClientEvent::EchoReply {
                 seq,