Honor the system default speech voice

tests/voice.test.cjs

@@ -117,17 +117,19 @@ test('recognition watchdog closes a session that never ends and permits retry',
   assert.equal(h.recognitions.length, 2);
 });
 
-test('TTS selects Swedish fallback, applies rate, and cancellation invalidates callbacks', () => {
+test('TTS uses the system default voice unless a named Swedish voice is selected', () => {
   const h = makeHarness();
   h.controller.update({mode: 'game-voice', rate: 1.4});
   assert.equal(h.controller.speak('Hej.'), true);
   const first = h.utterances[0];
   assert.equal(first.lang, 'sv-SE');
   assert.equal(first.rate, 1.4);
-  assert.equal(first.voice.name, 'Svensk');
+  assert.equal(first.voice, null);
   h.controller.cancelSpeech();
   first.onend();
   assert.equal(h.controller.getState(), 'IDLE');
+  assert.equal(h.controller.speak('Namngiven röst.', {voiceName: 'Svensk'}), true);
+  assert.equal(h.utterances.at(-1).voice.name, 'Svensk');
 });
 
 test('a player gesture restores the iOS speech primer after cancelling a queued reply', () => {