fix: no play-on-air button on CW

In CW the transmitter builds its tone from the keyer and ignores the DAX TX
audio path, so the button keyed the rig and sent silence. Confirmed on a Flex:
our side reported the playback as done while nothing went out.

Only the button goes. The row stays, or a CW operator who stopped their
recording would be left with no way to resume it — and the recording itself is
still worth keeping.

changelog.json

@@ -5,12 +5,14 @@
     "en": [
       "FlexRadio: in split, OpsLog stays on the receive slice instead of following the transmitter.",
       "QSO recording works on CW again. Your own sidetone is not in the file, the other station is.",
-      "Playing a recording on the air now says why when it cannot — most often no audio output to the radio is configured."
+      "Playing a recording on the air now says why when it cannot — most often no audio output to the radio is configured.",
+      "The play-on-air button is hidden on CW: the transmitter builds its tone from the keyer and ignores the audio path. Recording, stopping and resuming stay available."
     ],
     "fr": [
       "FlexRadio : en split, OpsLog reste sur la slice de réception au lieu de suivre l'émission.",
       "L'enregistrement des QSO fonctionne à nouveau en CW. Votre propre signal d'écoute n'est pas dans le fichier, celui du correspondant l'est.",
-      "L'émission d'un enregistrement indique désormais pourquoi elle échoue — le plus souvent aucune sortie audio vers la radio n'est configurée."
+      "L'émission d'un enregistrement indique désormais pourquoi elle échoue — le plus souvent aucune sortie audio vers la radio n'est configurée.",
+      "Le bouton d'émission de l'enregistrement est masqué en CW : l'émetteur fabrique sa tonalité à partir du manipulateur et ignore la chaîne audio. Enregistrer, arrêter et reprendre restent disponibles."
     ]
   },
   {

frontend/src/App.tsx

@@ -3739,17 +3739,24 @@ export default function App() {
       {/* A stopped take: play it to the station being worked, or carry on
           recording. Both sit where the counter is, which has shifted left to
           make room. */}
+      {/* A stopped take: resume it, and — on PHONE only — play it to the station
+          being worked. In CW the transmitter builds its tone from the keyer and
+          ignores the DAX TX audio path entirely, so the button would key the rig
+          and send silence. The row itself stays, or a CW operator who stopped
+          would be left with no way to resume. */}
       {recording && recStopped && RECORDABLE_MODES.has(mode.toUpperCase()) && (
         <span className="absolute right-2 top-1/2 -translate-y-1/2 z-10 inline-flex items-center gap-1.5">
-          <button
-            type="button"
-            onMouseDown={(e) => e.preventDefault()}
-            onClick={playRecordingOnAir}
-            title={t('rec.playOnAir')}
-            className="inline-flex items-center justify-center size-4 rounded text-success hover:bg-success/15"
-          >
-            ▶
-          </button>
+          {PHONE_MODES.has(mode.toUpperCase()) && (
+            <button
+              type="button"
+              onMouseDown={(e) => e.preventDefault()}
+              onClick={playRecordingOnAir}
+              title={t('rec.playOnAir')}
+              className="inline-flex items-center justify-center size-4 rounded text-success hover:bg-success/15"
+            >
+              ▶
+            </button>
+          )}
           <button
             type="button"
             onMouseDown={(e) => e.preventDefault()}