feat: the play button stops the transmission while it is going out

A second press restarted the message from the beginning. What the operator wants
there is to cut it short — enough heard, or pressed by mistake with the
transmitter keyed — and then to be able to send it again at once.

It now shows a stop square while playing and releases the PTT through the same
path the natural end uses, so nothing is left keyed. Together with the device
handover fixed a moment ago, sending again immediately afterwards works.

frontend/src/App.tsx

@@ -794,7 +794,15 @@ export default function App() {
   const resumeRecording = () => {
     QSOAudioResume().then((ok) => { if (ok) { setRecStopped(false); setRecTick((t) => t + 1); } }).catch(() => {});
   };
+  // One button, two jobs: play, and stop what is playing.
+  //
+  // A second press used to RESTART the message from the beginning. What an
+  // operator wants there is to cut it short — they have heard enough, or they
+  // pressed it by mistake with the transmitter keyed — and then to be able to
+  // send it again straight away. Stopping releases the PTT through the same
+  // path the natural end uses.
   const playRecordingOnAir = () => {
+    if (dvkStat.playing) { DVKStop(); return; }
     QSOAudioPlayOnAir().catch((e: any) => setError(String(e?.message ?? e)));
   };
   const refreshManualRecReady = () => { QSOAudioManualReady().then(setManualRecReady).catch(() => {}); };
@@ -3775,10 +3783,11 @@ export default function App() {
               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"
+              title={dvkStat.playing ? t('rec.stopPlaying') : t('rec.playOnAir')}
+              className={cn('inline-flex items-center justify-center size-4 rounded',
+                dvkStat.playing ? 'text-destructive hover:bg-destructive-muted' : 'text-success hover:bg-success/15')}
             >
-              ▶
+              {dvkStat.playing ? <span className="size-2 bg-current" /> : '▶'}
             </button>
           )}
           <button

frontend/src/lib/i18n.tsx

@@ -135,7 +135,7 @@ const en: Dict = {
   'imp.ctyDesc': "Recompute Country, DXCC & CQ/ITU zones from cty.dat, overriding the file — corrects what contest software exports wrong (e.g. RG2Y as Asiatic instead of European Russia). ClubLog's DXpedition overrides are applied on top per QSO date (e.g. TO974REF → Reunion, TO2A 2012 → French Guiana) whenever the ClubLog data is downloaded. Everything else in the ADIF is kept as-is. Tip: use Update duplicates to re-fix QSOs already in your log.",
   'imp.stationTitle': 'Fill my station fields from my profile',
   'imp.stationDesc': "Backfill empty MY_* fields (my grid, rig, antenna, address, city, state, county, SOTA/POTA ref, TX power…) plus Operator and Owner callsign from your active profile. Existing values are kept. Only STATION_CALLSIGN is left untouched so a mixed-call log isn't re-routed. It ALSO stamps your default confirmation statuses (paper QSL, LoTW, eQSL, Club Log, HRDLog, QRZ.com sent and received) on the ones the file leaves empty — a WSJT-X log carries almost none. Enable when importing your own log.",
-  'imp.cancel': 'Cancel', 'rec.manualStart': 'Record this contact. Automatic recording is off, so capture starts now \u2014 there is no pre-roll of what came before.', 'rec.stop': 'Stop the recording. The audio is kept and still saved with the QSO \u2014 stop it to play it back to the station you are working.', 'rec.resume': 'Carry on recording, appending to what is already captured.', 'rec.playOnAir': 'TRANSMIT the recording to the station you are working: keys the radio and sends it like a voice-keyer message.', 'rec.manualFailed': 'Recording could not be started \u2014 check the audio devices in Settings.', 'imp.mapAdd': 'The file puts a field in the wrong place\u2026', 'imp.mapTitle': 'Move fields on import', 'imp.mapDesc': 'Contest software stores the exchange where its own module keeps it. The RSGB IOTA contest exports the island reference in STATE \u2014 imported as-is it becomes a US state and the IOTA award stays empty. The destination is only filled where the file left it blank.', 'imp.mapMore': 'Add another', 'imp.import': 'Import',
+  'imp.cancel': 'Cancel', 'rec.manualStart': 'Record this contact. Automatic recording is off, so capture starts now \u2014 there is no pre-roll of what came before.', 'rec.stop': 'Stop the recording. The audio is kept and still saved with the QSO \u2014 stop it to play it back to the station you are working.', 'rec.resume': 'Carry on recording, appending to what is already captured.', 'rec.playOnAir': 'TRANSMIT the recording to the station you are working: keys the radio and sends it like a voice-keyer message.', 'rec.stopPlaying': 'Stop transmitting the recording', 'rec.manualFailed': 'Recording could not be started \u2014 check the audio devices in Settings.', 'imp.mapAdd': 'The file puts a field in the wrong place\u2026', 'imp.mapTitle': 'Move fields on import', 'imp.mapDesc': 'Contest software stores the exchange where its own module keeps it. The RSGB IOTA contest exports the island reference in STATE \u2014 imported as-is it becomes a US state and the IOTA award stays empty. The destination is only filled where the file left it blank.', 'imp.mapMore': 'Add another', 'imp.import': 'Import',
   'imp.progressTitle': 'Importing ADIF…', 'bulk.progressTitle': 'Updating the selected QSOs\u2026',
   'imp.progressCount': '{done} / {tot} records · {pct}%', 'imp.progressCountOnly': '{done} records…',
   'imp.complete': 'Import complete.',
@@ -546,7 +546,7 @@ const fr: Dict = {
   'imp.ctyDesc': "Recalcule Pays, DXCC & zones CQ/ITU depuis cty.dat, en écrasant le fichier — corrige ce que les logiciels de contest exportent mal (ex. RG2Y en Russie asiatique au lieu d'européenne). Les exceptions DXpédition de ClubLog s'appliquent par-dessus selon la date du QSO (ex. TO974REF → Réunion, TO2A 2012 → Guyane française) dès que les données ClubLog sont téléchargées. Tout le reste de l'ADIF est conservé tel quel. Astuce : utilise Mettre à jour les doublons pour re-corriger des QSO déjà dans le log.",
   'imp.stationTitle': 'Remplir mes champs station depuis mon profil',
   'imp.stationDesc': "Complète les champs MY_* vides (locator, rig, antenne, adresse, ville, état, comté, réf. SOTA/POTA, puissance TX…) plus Opérateur et Indicatif propriétaire depuis le profil actif. Les valeurs existantes sont conservées. Seul STATION_CALLSIGN n'est jamais touché pour ne pas re-router un log multi-indicatifs. Elle applique AUSSI tes statuts de confirmation par défaut (QSL papier, LoTW, eQSL, Club Log, HRDLog, QRZ.com envoyé et reçu) sur ceux que le fichier laisse vides — un log WSJT-X n'en contient pratiquement aucun. À activer quand tu importes ton propre log.",
-  'imp.cancel': 'Annuler', 'rec.manualStart': 'Enregistrer ce contact. L\u2019enregistrement automatique est d\u00e9sactiv\u00e9 : la capture commence maintenant, sans les secondes qui pr\u00e9c\u00e8dent.', 'rec.stop': 'Arr\u00eater l\u2019enregistrement. L\u2019audio est conserv\u00e9 et sera enregistr\u00e9 avec le QSO \u2014 arr\u00eatez-le pour le repasser \u00e0 la station travaill\u00e9e.', 'rec.resume': 'Reprendre l\u2019enregistrement, \u00e0 la suite de ce qui est d\u00e9j\u00e0 captur\u00e9.', 'rec.playOnAir': '\u00c9METTRE l\u2019enregistrement vers la station travaill\u00e9e : passe la radio en \u00e9mission et l\u2019envoie comme un message du manipulateur vocal.', 'rec.manualFailed': 'L\u2019enregistrement n\u2019a pas pu d\u00e9marrer \u2014 v\u00e9rifiez les p\u00e9riph\u00e9riques audio dans les R\u00e9glages.', 'imp.mapAdd': 'Le fichier met un champ au mauvais endroit\u2026', 'imp.mapTitle': 'D\u00e9placer des champs \u00e0 l\u2019import', 'imp.mapDesc': 'Les logiciels de concours rangent l\u2019\u00e9change l\u00e0 o\u00f9 leur module le garde. Le contest IOTA de la RSGB exporte la r\u00e9f\u00e9rence d\u2019\u00eele dans STATE \u2014 import\u00e9e telle quelle elle devient un \u00e9tat am\u00e9ricain et le dipl\u00f4me IOTA reste vide. La destination n\u2019est remplie que l\u00e0 o\u00f9 le fichier l\u2019a laiss\u00e9e vide.', 'imp.mapMore': 'Ajouter une ligne', 'imp.import': 'Importer',
+  'imp.cancel': 'Annuler', 'rec.manualStart': 'Enregistrer ce contact. L\u2019enregistrement automatique est d\u00e9sactiv\u00e9 : la capture commence maintenant, sans les secondes qui pr\u00e9c\u00e8dent.', 'rec.stop': 'Arr\u00eater l\u2019enregistrement. L\u2019audio est conserv\u00e9 et sera enregistr\u00e9 avec le QSO \u2014 arr\u00eatez-le pour le repasser \u00e0 la station travaill\u00e9e.', 'rec.resume': 'Reprendre l\u2019enregistrement, \u00e0 la suite de ce qui est d\u00e9j\u00e0 captur\u00e9.', 'rec.playOnAir': '\u00c9METTRE l\u2019enregistrement vers la station travaill\u00e9e : passe la radio en \u00e9mission et l\u2019envoie comme un message du manipulateur vocal.', 'rec.stopPlaying': 'Arrêter l’émission de l’enregistrement', 'rec.manualFailed': 'L\u2019enregistrement n\u2019a pas pu d\u00e9marrer \u2014 v\u00e9rifiez les p\u00e9riph\u00e9riques audio dans les R\u00e9glages.', 'imp.mapAdd': 'Le fichier met un champ au mauvais endroit\u2026', 'imp.mapTitle': 'D\u00e9placer des champs \u00e0 l\u2019import', 'imp.mapDesc': 'Les logiciels de concours rangent l\u2019\u00e9change l\u00e0 o\u00f9 leur module le garde. Le contest IOTA de la RSGB exporte la r\u00e9f\u00e9rence d\u2019\u00eele dans STATE \u2014 import\u00e9e telle quelle elle devient un \u00e9tat am\u00e9ricain et le dipl\u00f4me IOTA reste vide. La destination n\u2019est remplie que l\u00e0 o\u00f9 le fichier l\u2019a laiss\u00e9e vide.', 'imp.mapMore': 'Ajouter une ligne', 'imp.import': 'Importer',
   'imp.progressTitle': 'Import ADIF en cours…', 'bulk.progressTitle': 'Mise \u00e0 jour des QSO s\u00e9lectionn\u00e9s\u2026',
   'imp.progressCount': '{done} / {tot} enregistrements · {pct}%', 'imp.progressCountOnly': '{done} enregistrements…',
   'imp.complete': 'Import terminé.',