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/clearpilot/dashcamd.cc

@@ -118,6 +118,10 @@ static std::string srt_time(int seconds) {
 int main(int argc, char *argv[]) {
   setpriority(PRIO_PROCESS, 0, -10);
 
+  // Reset OMX subsystem — clears any stale encoder state from previous unclean exit
+  OMX_Deinit();
+  OMX_Init();
+
   // Ensure base output directory exists
   mkdir(VIDEOS_BASE.c_str(), 0755);
 
@@ -341,6 +345,16 @@ int main(int argc, char *argv[]) {
 
     uint64_t ts = nanos_since_boot() - segment_start_ts;
 
+    // Validate buffer before encoding
+    if (buf->y == nullptr || buf->uv == nullptr || buf->width == 0 || buf->height == 0) {
+      LOGE("dashcamd: invalid frame buf y=%p uv=%p %zux%zu, skipping", buf->y, buf->uv, buf->width, buf->height);
+      continue;
+    }
+
+    if (frame_count == 0) {
+      LOGW("dashcamd: first encode w=%d h=%d stride=%d buf_y=%p buf_uv=%p", width, height, y_stride, buf->y, buf->uv);
+    }
+
     // Feed NV12 frame directly to OMX encoder
     encoder->encode_frame_nv12(buf->y, y_stride, buf->uv, uv_stride, width, height, ts);
     frame_count++;