port dashcamd: hardware-encoded MP4 dashcam

VisionIPC frames from camerad → OMX H.264 hardware encoder → 3-min MP4
segments + SRT GPS subtitles in /data/media/0/videos/<trip>/. Manages
its own trip lifecycle (WAITING/RECORDING/IDLE_TIMEOUT) and writes
DashcamState/DashcamFrames memory params for the UI's Status window.
Honors DashcamShutdown for graceful close before power-off.

Files added:
- selfdrive/clearpilot/dashcamd.cc + SConscript

Files modified:
- selfdrive/frogpilot/screenrecorder/omx_encoder.{cc,h}: ported broken's
  version, which adds encode_frame_nv12() (direct NV12 input from camerad,
  alongside the existing encode_frame_rgba used by the disabled screen
  recorder) and simplifies the libyuv conversion paths to NEON-only since
  this device is aarch64.
- selfdrive/SConscript: register selfdrive/clearpilot/SConscript so the
  dashcamd binary is part of the build.
- selfdrive/manager/process_config.py:
  - camerad gating driverview → always_run so dashcamd can record the
    moment ignition+drive arrives without waiting for camera startup.
  - Register dashcamd as NativeProcess gated always_run.
- system/loggerd/deleter.py:
  - MIN_BYTES 5 GB → 9 GB to leave headroom for dashcam footage.
  - delete_oldest_video(): trip-aware cleanup. Drops entire oldest trip
    dir first; if only the active trip remains, drops oldest segment
    inside it; cleans up legacy flat .mp4s too.
  - cleanup_log2(): keeps /data/log2 session logs under 4 GB total.
  - Hooked into deleter_thread: video first when out of bytes/percent;
    log2 quota check on the idle path. New code uses print(stderr) per
    the no-cloudlog rule.

Verified: built clean, manager started, dashcamd in WAITING state
(DashcamState=waiting, DashcamFrames=0), camerad running, no errors.

selfdrive/frogpilot/screenrecorder/omx_encoder.h

@@ -12,13 +12,15 @@ 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);
+  int encode_frame_nv12(const uint8_t *y_ptr, int y_stride, const uint8_t *uv_ptr, int uv_stride,
+                        int in_width, int in_height, uint64_t ts);
   void encoder_open(const char* filename);
   void encoder_close();
 
@@ -42,31 +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;
 };