fix: correct iterator variable shadowing in multi_arm_reacher causing TypeError on pause/stop

[AnishKamatam]

Summary

This PR fixes a crash in the multi_arm_reacher example when pressing "Pause" or "Stop" after the robot begins moving.

Fixes #372

Environment

• cuRobo installation mode: isaac sim
• Python: native 3.10 (bundled with Isaac Sim 4.1.0)
• Isaac Sim: 4.1.0

Steps to Reproduce

1. Launch multi_arm_reacher example

2. Press Play

3. Move the red cube so the arms start moving

4. Press Pause or Stop

5. Crash occurs with:

   TypeError: not all arguments converted during string formatting

Cause

The example uses an out-of-scope iterator variable i, which leads to incorrect formatting behavior inside a conditional.

Fix

Replaced the incorrect iterator name with a scoped variable (k) inside the loop:

for k in target_links.keys():
    c_p, c_rot = target_links[k].get_world_pose()
    link_poses[k] = Pose(
        position=tensor_args.to_device(c_p),
        quaternion=tensor_args.to_device(c_rot),
    )