Add retries while recording motor ranges

[tom-doerr]

Summary

• retry transient sync-read failures while recording motor range calibration
• add a short delay between live range display refreshes to avoid hammering the serial bus

Test

• python -m py_compile src/lerobot/motors/motors_bus.py
• manually calibrated an SO-100 follower arm after hitting intermittent Feetech status packet drops

[Copilot]

Pull request overview

This PR improves robustness and bus load during interactive motor range-of-motion calibration by adding retries to transient sync-read failures and throttling the live display refresh loop.

Changes:

• Add num_retry=5 to sync_read("Present_Position", ...) calls during record_ranges_of_motion().
• Insert a short time.sleep(0.02) delay between console refreshes to reduce serial bus hammering.
• Import time to support the refresh delay.

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