Add TEST_ENTER/TEST_EXIT commands via BLE to enter/exit test mode.
In test mode, inference results are suppressed; testers can directly
trigger BLE JSON (TEST_BLE *), CAN+Buzzer actions (TEST_CAN *),
or run sequenced full-coverage tests (TEST_BLE_ALL, TEST_CAN_ALL,
TEST_ALL). Auto-exits after 60s idle. Routes unrecognised BLE
commands through new bt_uart_set_extra_cmd_cb() hook.
- app_header_init: detect vehicle(class=2) in print_yolo_result(),
send CAN speed=10 on detection, speed=240 on clear;
only triggers on state change, keepalive maintains cmd
- app_header_init: on speed state change, send BLE JSON
{response_type:can_status, content:{vehicle_detected, speed_cmd}}
- app_header_init: add #include can_bus.h / bt_uart.h
- event_recorder: wrap legacy MsgBroker IPC path in #if 0;
setSpeed now goes directly through can_bus_send_control_cmd()
