fix: PCM copy, device name encoding, double shutdown

- playRawPcm: ma_audio_buffer_init_copy instead of ma_audio_buffer_ref (copies PCM)
- enumerateDevices: fromLocal8Bit instead of fromUtf8 for device names
- AudioRecorder: m_deviceStarted flag prevents double ma_device_uninit
- stopMicTest: delete instead of deleteLater to avoid deferred double shutdown

tools/chatgui/src/audiorecorder.cpp

@@ -56,11 +56,13 @@ bool AudioRecorder::init() {
 }
 
 void AudioRecorder::shutdown() {
+    if (!m_initialized) return;
     if (m_recording) stopRecording();
-    if (m_device) {
-        delete m_device;
-        m_device = nullptr;
+    if (m_deviceStarted) {
+        m_deviceStarted = false;
+        if (m_device) { ma_device_stop(m_device); ma_device_uninit(m_device); }
     }
+    if (m_device) { delete m_device; m_device = nullptr; }
     m_initialized = false;
     qDebug("AudioRecorder: shutdown");
 }
@@ -113,6 +115,7 @@ void AudioRecorder::startRecording() {
     }
 
     m_recording = true;
+    m_deviceStarted = true;
     m_durationTimer.start();
     qDebug("AudioRecorder: recording started");
     emit recordingStarted();
@@ -122,8 +125,11 @@ void AudioRecorder::stopRecording() {
     if (!m_recording) return;
 
     m_durationTimer.stop();
-    ma_device_stop(m_device);
-    ma_device_uninit(m_device);
+    if (m_deviceStarted) {
+        ma_device_stop(m_device);
+        ma_device_uninit(m_device);
+        m_deviceStarted = false;
+    }
 
     m_recording = false;
     int duration = m_elapsedMs;