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.h

@@ -20,7 +20,7 @@ public:
   struct StatusData {
     QString time, storage, ram, load, temp, fan, ip, wifi;
     QString vpn_status, vpn_ip, gps, telemetry;
-    QString dashcam_status, dashcam_size;
+    QString dashcam_status, dashcam_frames;
     float temp_c = 0;
   };