unify voice waveform format: base64 wf={100chars};dur={ms}; for both desktop and Android

- inputbar.cpp: CSV waveform → base64 log-scale (same as voice_recorder.c)
- messagelist.cpp: sendVoiceMessage removes displayName|dur_sec| prefix, uses wfStr directly
  setVoiceMessageRoles: decodes new format wf={base64};dur={ms};|... from data field
- messagedelegate.cpp: waveform values now pre-normalized 0..1, no log recalculation needed
- VoiceEncoder: no changes needed (was already compatible)

Both platforms now store identical format in chat_msg_submit.data:
  wf=ABCDef...100chars;dur=NNNN;|file_size|block_size|num_blocks|sigs_hex

tools/chatgui/src/inputbar.cpp

@@ -250,7 +250,8 @@ void InputBar::onPttReleased() {
     m_voiceFilePath = QString("%1/%2_%3_%4.%5").arg(mediaPath, blk.dt, blk.basename, blk.suffix, blk.ext);
 
     const auto& wf = m_recorder->waveformLevels();
-    QString wfStr;
+    QString wfStr = "wf=";
+    static const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
     int N = (int)wf.size();
     for (int i = 0; i < 100; i++) {
         int s = i * N / 100, e = (i + 1) * N / 100;
@@ -260,9 +261,12 @@ void InputBar::onPttReleased() {
         float sum = 0; int cnt = 0;
         for (int j = s; j < e; j++) { sum += wf[j]; cnt++; }
         float v = cnt > 0 ? sum / cnt : 0;
-        if (i > 0) wfStr += ',';
-        wfStr += QString::number(v, 'f', 3);
+        float db = v > 0.00001f ? 20.0f * log10f(v) : -100.0f;
+        int idx = (int)((db + 60.0f) / 60.0f * 64.0f);
+        if (idx < 0) idx = 0; if (idx > 63) idx = 63;
+        wfStr += b64[idx];
     }
+    wfStr += QString(";dur=%1;").arg(durationMs);
     GUI_INFO("InputBar: voice message ready: dt=%s stem=%s blocks=%d dur=%.1fs",
              qPrintable(blk.dt), qPrintable(blk.basename), blk.numBlocks, durationSec);
     emit sendVoiceMessage(blk.dt, blk.basename, blk.suffix, blk.ext,