fix: call tts issue

src/lib/components/chat/MessageInput/CallOverlay.svelte

@@ -456,7 +456,9 @@
 				if ($config.audio.tts.engine !== '') {
 					const res = await synthesizeOpenAISpeech(
 						localStorage.token,
-						$settings?.audio?.tts?.voice ?? $config?.audio?.tts?.voice,
+						$settings?.audio?.tts?.defaultVoice === $config.audio.tts.voice
+							? ($settings?.audio?.tts?.voice ?? $config?.audio?.tts?.voice)
+							: $config?.audio?.tts?.voice,
 						content
 					).catch((error) => {
 						console.error(error);