fix: improve board zoom implementation to scale cards & columns

[jynxbt]

#708

[trobonox]

Thanks for the contribution! I'll review the code and test if everything works fine and let you know if there's any tweaks that need to be made.

Also as a quick side note: I would recommend you to sign your commits with a GPG key (this is a requirement for contributing to Kanri and also for many other projects).
Since it's your first time contributing to Kanri you don't need to worry about it this time, but if you wish to contribute more in the future please sign your commits.

[jynxbt]

i’ll make sure to sign my commits in the future. appreciate the heads-up, bro

[trobonox]

Everything looks good to me, thanks for your contribution!