fix: port OmxEncoder safety fixes from upstream FrogPilot

- OMX_Init/OMX_Deinit managed per encoder instance lifecycle
- Proper error handling in constructor, encoder_open, encoder_close
- Null guards on done_out.pop() and handle in destructor
- Codec config written directly to codecpar (no codec_ctx)
- ffmpeg faststart remux on segment close
- Crash handler in dashcamd for diagnostics
- DashcamFrames param for live frame count in status window

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/ui/qt/window.cc

@@ -266,7 +266,7 @@ static StatusWindow::StatusData collectStatus() {
   // Dashcam
   QString dashcam_pid = shellCmd("pgrep -x dashcamd");
   d.dashcam_status = dashcam_pid.isEmpty() ? "stopped" : "recording";
-  d.dashcam_size = shellCmd("du -sh /data/media/0/videos 2>/dev/null | awk '{print $1}'");
+  d.dashcam_frames = readFile("/dev/shm/params/d/DashcamFrames");
 
   // Panda: checked on UI thread in applyResults() via scene.pandaType
 
@@ -385,7 +385,7 @@ void StatusWindow::applyResults() {
 
   if (d.dashcam_status == "recording") {
     QString text = "Recording";
-    if (!d.dashcam_size.isEmpty()) text += " (" + d.dashcam_size + ")";
+    if (!d.dashcam_frames.isEmpty() && d.dashcam_frames != "0") text += " (" + d.dashcam_frames + " frames)";
     dashcam_label->setText(text);
     dashcam_label->setStyleSheet("color: #17c44d; font-size: 38px;");
   } else {