improves the battery segment on Linux systems with multiple batteries

[akunbeben]

Hi,

This PR improves the battery segment on Linux systems by properly handling devices with multiple batteries (such as ThinkPad laptops with both internal and external batteries).

What changed:

• Instead of checking only BAT0 or BAT1, the script now loops through all available /sys/class/power_supply/BAT* devices.
• It sums the charge_now and charge_full (or energy_now and energy_full) values across all batteries to calculate an accurate total percentage.

Why:

On devices like the ThinkPad T480, this improves the accuracy of the battery indicator since both internal and external batteries are used together.

This change preserves existing behavior for systems with only one battery, and should be backwards compatible.

Thanks.

[erikw]

This looks great. Thank you for caring about backwards compatability!