fix: voice message display, playback, recording UI, audio settings

- messagelist: parse content_type from JSON when DB column is empty
- messagelist: recording indicator (red dot + timer + cancel button)
- messagedelegate: editorEvent for play/pause toggle + progress bar
- messagedelegate: VoicePlayState tracking with QTimer
- InputBar: proper recordingContext (mediaDir + channelId)
- DbManager: dbPath() for media directory resolution
- AudioRecorder: peakLevel() for mic level meter
- VoiceEncoder: codec quality presets (Low/Standard/High)
- audiodevicesettingspage: Default device option first
- audiodevicesettingspage: mic level meter + test microphone
- audiodevicesettingspage: test speaker button
- audiodevicesettingspage: codec preset combo (Low/Standard/High)
- mainwindow: load opus_codec_preset from ui_state on startup

tools/chatgui/src/voicemessageencoder.cpp

@@ -11,9 +11,21 @@ extern "C" {
 #include <cstring>
 
 static const int FRAME_MS = 20;
-static const uint32_t OPUS_MAGIC = 0x5355504F; /* "OPUS" */
+static const uint32_t OPUS_MAGIC = 0x5355504F;
 static const int MAX_PACKET = 4000;
 
+static int s_preset = 1; /* 0=Low, 1=Standard, 2=High */
+static const int s_bitrates[]   = {16000, 32000, 64000};
+static const int s_complexities[] = {2, 5, 10};
+
+void VoiceEncoder::setPreset(int preset) {
+    if (preset < 0) preset = 0;
+    if (preset > 2) preset = 2;
+    s_preset = preset;
+}
+
+int VoiceEncoder::preset() { return s_preset; }
+
 int VoiceEncoder::encodeToFile(const std::vector<int16_t>& pcm, int sampleRate, int channels,
                                 const QString& filePath, float& outDurationSec) {
     if (pcm.empty() || sampleRate <= 0 || channels <= 0) {
@@ -30,6 +42,8 @@ int VoiceEncoder::encodeToFile(const std::vector<int16_t>& pcm, int sampleRate,
         qWarning("VoiceEncoder: encoder create failed");
         return -1;
     }
+    opus_codec_encoder_bitrate_set(enc, s_bitrates[s_preset]);
+    opus_codec_encoder_complexity_set(enc, s_complexities[s_preset]);
 
     QFile file(filePath);
     if (!file.open(QIODevice::WriteOnly)) {