Update main.py

[slfagrouche]

BitGen with contributions feat:add rate-limit handling ,error messages and progress indicator

I added rate-limit handling for API requests ,which improved error messages for better user feedback ,and a progress indicator when checking empty wallets in non-verbose mode. Now basically the script waits for aminute if rate-limited, then shows informative error messages for API-request failures and displays a progress indicator in nonverbose mode when checking emptywallets.

The contributions: -Added check_balance_btc_with_rate_limit() for rate-limit handling -Improved error messages for API request failures -Added progress indicator for non-verbose mode