dashcamd v3: trip directories, state machine, graceful shutdown

Dashcam recording now organized by trip in /data/media/0/videos/YYYYMMDD-HHMMSS/.
Starts recording immediately on launch (with 10-min idle timer), transitions to
continuous recording when drive gear detected. New trip on every ignition cycle.
Graceful shutdown via DashcamShutdown param with 15s ack timeout in thermald.

- Bitrate reduced to 2500 kbps (was 4 Mbps)
- Trip state machine: IDLE → RECORDING ↔ IDLE_TIMEOUT → TRIP_ENDED
- Deleter: trip-aware deletion (oldest trip first, then segments within active trip)
- camerad changed to always_run (was driverview) so dashcam works offroad
- DashcamShutdown param for graceful close before device power-off

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/manager/process_config.py

@@ -59,7 +59,7 @@ def dashcam_should_run(started, params, CP: car.CarParams) -> bool:
 procs = [
   DaemonProcess("manage_athenad", "selfdrive.athena.manage_athenad", "AthenadPid"),
 
-  NativeProcess("camerad", "system/camerad", ["./camerad"], driverview),
+  NativeProcess("camerad", "system/camerad", ["./camerad"], always_run),
   NativeProcess("logcatd", "system/logcatd", ["./logcatd"], allow_logging),
   NativeProcess("proclogd", "system/proclogd", ["./proclogd"], allow_logging),
   PythonProcess("logmessaged", "system.logmessaged", allow_logging),