fix: logarithmic waveform scale + visible idle color + duration display

- Waveform bars: linear→logarithmic (dB mapping -60..0dB)
- Colors: idle gray visible (130 alpha), played blue, unplayed dim blue
- Min bar height: 1→2px
- Duration: fallback to MsgVoiceDurationRole when not playing (was 0:00/0:00)
- Debug log: wfN, width, first value, dB, barH

tools/chatgui/src/messagedelegate.cpp

@@ -622,6 +622,10 @@ void MessageDelegate::paint(QPainter *painter, const QStyleOptionViewItem &optio
 
         /* compute elapsed/frac for progress */
         float elapsed = 0, frac = 0, durSec = st.durationSec;
+        if (durSec <= 0) {
+            QString ds = index.data(MsgVoiceDurationRole).toString();
+            ds.remove('s'); durSec = ds.toFloat();
+        }
         if (isPaused) {
             elapsed = st.pausedPosSec;
         } else if (isPlaying) {
@@ -662,16 +666,24 @@ void MessageDelegate::paint(QPainter *painter, const QStyleOptionViewItem &optio
         QRect wfR = L.voiceWaveformRect;
         if (wfN > 0) {
             float barW = (float)wfR.width() / wfN;
-            int ph = wfR.height() - 3;  /* leave 3px for progress bar at bottom */
+            int ph = wfR.height() - 3;
             for (int i = 0; i < wfN; i++) {
                 float v = wf[i].toFloat();
-                int barH = 1 + (int)(v * (ph - 1));
+                float db = v > 0.00001f ? 20.0f * log10f(v) : -100.0f;
+                float logV = (db + 60.0f) / 60.0f;
+                if (logV < 0) logV = 0; if (logV > 1) logV = 1;
+                int barH = 2 + (int)(logV * (ph - 2));
                 int x = wfR.left() + (int)(i * barW);
                 int y = wfR.top() + ph - barH;
                 int bw = qMax(2, (int)(barW * 0.8f));
                 bool before = wfN > 0 && (float)i / wfN <= frac;
-                painter->setBrush(before ? QColor(0x33, 0x90, 0xEC) : QColor(0x33, 0x90, 0xEC, 45));
+                QColor played(0x33, 0x90, 0xEC);
+                QColor unplayed(0x33, 0x90, 0xEC, 80);
+                QColor idle(0x70, 0x70, 0x78, 130);
+                painter->setBrush((isPlaying || isPaused) ? (before ? played : unplayed) : idle);
                 painter->drawRect(QRect(x, y, bw, barH));
+                if (i == 0) GUI_DEBUG("voice paint: wfN=%d wfW=%d v=%.3f dB=%.1f logV=%.2f barH=%d",
+                                      wfN, wfR.width(), v, db, logV, barH);
             }
         }