feat(decodes): arrival order within a period, not strongest-first

The panel now mirrors the decoder's own window line for line — the operator
compares the two side by side, and the SNR sort scrambled that
correspondence. The report is still right there in its column.

frontend/src/components/DecodesPanel.tsx

@@ -498,10 +498,11 @@ function buildPeriods(filtered: Decode[], txMsgs: TxMsg[]) {
       // the same way it was grouped.
       tr: trSeconds(g.decodes[0]?.mode ?? g.tx[0]?.mode, g.decodes[0]?.tr_period),
       tx: g.tx,
-      // Strongest first inside a period: the eye should land on what is
-      // workable, and time within a slot means nothing — they were all
-      // transmitting simultaneously.
-      decodes: g.decodes.sort((x, y) => y.snr - x.snr),
+      // ARRIVAL order inside a period, per the operator: it mirrors the
+      // decoder's own window line for line, which makes the two screens
+      // comparable at a glance — the strongest-first sort scrambled that
+      // correspondence, and SNR is right there in its column anyway.
+      decodes: g.decodes,
     }));
 }