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/frogpilot/screenrecorder/screenrecorder.cc

@@ -27,7 +27,7 @@ ScreenRecorder::ScreenRecorder(QWidget *parent) : QPushButton(parent), image_que
 
 void ScreenRecorder::initializeEncoder() {
   const std::string path = "/data/media/0/videos";
-  encoder = std::make_unique<OmxEncoder>(path.c_str(), recording_width, recording_height, 60, 2 * 1024 * 1024, false, false);
+  encoder = std::make_unique<OmxEncoder>(path.c_str(), recording_width, recording_height, 60, 2 * 1024 * 1024);
 }
 
 ScreenRecorder::~ScreenRecorder() {