Add saltybot_can_e2e_test package with 64 tests covering the full Orin↔Mamba↔VESC CAN pipeline: drive commands, heartbeat timeout, e-stop escalation, mode switching, and FC_VESC status broadcasts. Tests run with plain pytest — no ROS2 or real CAN hardware required. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>