Optimize KCardGrid's internal usage of watchers

[MisRob]

Summary

In #796, I experienced problems with reactivity when using computed in some places. I was able to track it to useKResponsiveWindow, but am still not clear what exactly was going on. I temporarily resolved it by using watch even in places that would benefit from computed. The goal of this issue is to audit all watchers in lib/cards files and refactor to computed where possible or debug and comment on why watch has to be used exactly.

The Value Add

• Reduces tech debt
• computed model is more intuitive in some places
• computed is generally more performant than watch