[Feature Request] Add ability to run custom scripts/commands when a timer starts or ends

[flubberding]

Hello,

First of, thanks for the great productivity tool! Pomotroid is great and I've recommended it to many people.

However, the only functionality that I miss is the ability to run a custom script when a timer starts or ends. I've used the Fokus Plasmoid in the past, that looks similar and has this functionality, but I'm moving away from KDE Plasma in favor of i3-gaps, thus using a plasmoid isn't ideal for me any more.

In Fokus you can set it up to run a script when a focus timer starts or ends, when a break timer starts or ends or when you pres the stop button (Screenshot of settings). This was really helpful as it allowed me to write my own "productivity mode" script.

For instance, When I started a productivity timer, it would start playing one of my audio-files that help me focus with mocp and it would switch KDE Plasma to my productivity activity (changing my background, widget and open programs ect.). When the timer ran out, mocp paused the music and it would switch back to my regular activity.

I hope my description is clear enough. If not or if I can help in any other way, please let me know.