Hide/show menu bar item based on battery percentage

**Is your feature request related to a problem? Please describe.**

Two things:
- I want to keep my menu bar as distraction free as possible
- I would like want a subtle reminder if my battery is falling below a certain percentage (since that's just as important for battery health)

**Describe the solution you'd like**
I'd like to be able to hide the menu bar item conditionally based on a certain battery percentage, e.g. only show it when it falls below 40%.

**Describe alternatives you've considered**
I've been using Bartender to do this, but it's not working right on macOS 26 and I'd like to switch away from it.