Add motor telemetry (temperature/current) for RMD & SMC, update README

[dwarakeshbaraneetharan]

Summary

• Motor telemetry state interfaces: Both RMD and SMC hardware interfaces now expose motor_temperature (°C) and torque_current (A) as state interfaces per joint. These are decoded from the existing CAN reply frames (commands 0xA2, 0xA4, 0x9C all share the same response layout). Published automatically via joint_state_broadcaster on /dynamic_joint_states.
• XACRO declarations: Added <state_interface name="motor_temperature"/> and <state_interface name="torque_current"/> to all joints in arm.rmd.ros2_control.xacro and arm.smc.ros2_control.xacro.
• Logger output: Both RMD and SMC loggers now display temperature and torque current alongside existing joint data.
• README overhaul: Restructured with hardware setup, CAN setup, build instructions, controller switching docs, and removed outdated sections.
• Added src/tools/scripts/can_setup.sh

[IshanDutta11]

Looks mostly good, but you are missing the actual motor state broadcaster. The state interfaces exist, but we want the status broadcaster to display these. I'm thinking you make a subsystem folder called general, have a controllers package in it, and create the motor status broadcaster here. Access this plugin in all of the other subsystems so you don't need to repeat code. If you find another better way, you can do that too and I'll review it.

[IshanDutta11]

This is mostly correct. I will approve this for now, but remember that you need to activate this controller in arm, drive, and science. That itself shouldn't take too long and this broadcaster is not super integral, so we can continue that later, just keep it in mind.