obd-poller over the K-line via the Bluetooth ELM327; gnss publisher; elm_connected

obd-poller drops its CAN socket: the Z27AG answers OBD-II only on ISO 9141-2.
It holds a raw RFCOMM link to the ELM (no pairing, no root), fixes the protocol
(ATSP3) so nothing probes CAN, publishes the obd_* signals, and releases the
adapter after a minute of ECU silence so it can sleep.
gnss: gpsd's fix as yukart/gnss/<signal>. orin-status: elm_connected from BlueZ.
One native deploy script (deploy-native.sh BIN) behind the per-service ones;
/etc/default/yukart-elm holds the adapter's address.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

deploy/yukart-elm.default

@@ -0,0 +1,5 @@
+# The ELM327 (OBD-II on the K-line, over Bluetooth serial): its address, read by
+# yukart-obd-poller (which connects) and yukart-orin-status (which only watches).
+# Installed to /etc/default/yukart-elm by scripts/deploy-native.sh when absent;
+# edit it there for another adapter, then restart both services.
+ELM_ADDR=00:0C:BF:50:AF:3F