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/omx_encoder.h

@@ -12,10 +12,10 @@ extern "C" {
 
 #include "common/queue.h"
 
-// OmxEncoder, lossey codec using hardware hevc
+// OmxEncoder, lossey codec using hardware H.264
 class OmxEncoder {
 public:
-  OmxEncoder(const char* path, int width, int height, int fps, int bitrate, bool h265, bool downscale);
+  OmxEncoder(const char* path, int width, int height, int fps, int bitrate);
   ~OmxEncoder();
 
   int encode_frame_rgba(const uint8_t *ptr, int in_width, int in_height, uint64_t ts);
@@ -44,31 +44,26 @@ private:
   int counter = 0;
 
   std::string path;
-  FILE *of;
+  FILE *of = nullptr;
 
-  size_t codec_config_len;
-  uint8_t *codec_config = NULL;
-  bool wrote_codec_config;
+  size_t codec_config_len = 0;
+  uint8_t *codec_config = nullptr;
+  bool wrote_codec_config = false;
 
   std::mutex state_lock;
   std::condition_variable state_cv;
   OMX_STATETYPE state = OMX_StateLoaded;
 
-  OMX_HANDLETYPE handle;
+  OMX_HANDLETYPE handle = nullptr;
 
   std::vector<OMX_BUFFERHEADERTYPE *> in_buf_headers;
   std::vector<OMX_BUFFERHEADERTYPE *> out_buf_headers;
 
-  uint64_t last_t;
+  uint64_t last_t = 0;
 
   SafeQueue<OMX_BUFFERHEADERTYPE *> free_in;
   SafeQueue<OMX_BUFFERHEADERTYPE *> done_out;
 
-  AVFormatContext *ofmt_ctx;
-  AVCodecContext *codec_ctx;
-  AVStream *out_stream;
-  bool remuxing;
-
-  bool downscale;
-  uint8_t *y_ptr2, *u_ptr2, *v_ptr2;
+  AVFormatContext *ofmt_ctx = nullptr;
+  AVStream *out_stream = nullptr;
 };