fix: dashcamd OMX crash on restart, add dashcam status indicator

- Reset OMX subsystem (Deinit/Init) on dashcamd startup to clear stale
  encoder state from previous unclean exits
- Validate OMX output buffers before memcpy to prevent segfault
- Validate VisionBuf frame data before encoding
- Add dashcam row to status window showing recording state and disk usage

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

selfdrive/ui/qt/window.cc

@@ -263,6 +263,11 @@ static StatusWindow::StatusData collectStatus() {
   // Telemetry
   d.telemetry = readFile("/data/params/d/TelemetryEnabled");
 
+  // 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}'");
+
   // Panda: checked on UI thread in applyResults() via scene.pandaType
 
   return d;
@@ -305,6 +310,7 @@ StatusWindow::StatusWindow(QWidget *parent) : QFrame(parent) {
   vpn_label = makeRow("VPN");
   gps_label = makeRow("GPS");
   telemetry_label = makeRow("Telemetry");
+  dashcam_label = makeRow("Dashcam");
 
   layout->addStretch();
 
@@ -376,6 +382,16 @@ void StatusWindow::applyResults() {
     telemetry_label->setText("Disabled");
     telemetry_label->setStyleSheet("color: grey; font-size: 38px;");
   }
+
+  if (d.dashcam_status == "recording") {
+    QString text = "Recording";
+    if (!d.dashcam_size.isEmpty()) text += " (" + d.dashcam_size + ")";
+    dashcam_label->setText(text);
+    dashcam_label->setStyleSheet("color: #17c44d; font-size: 38px;");
+  } else {
+    dashcam_label->setText("Stopped");
+    dashcam_label->setStyleSheet("color: #ff4444; font-size: 38px;");
+  }
 }
 
 void StatusWindow::mousePressEvent(QMouseEvent *e) {