Add toggle for dark and light mode - part 2

[swyxio]

this incorpoates #96 thanks to @eshack94 and @seanoliver

we have some known bugs we decided to fix later:

• when first opens up, everyone opens to system default, only waiting to keypress to toggle darkmode. this means anthropic, which doesnt have a dark mode, shows up light first while everyone else is dark
• "toggle dark mode" menubar item isnt perfectly synced with the actual ui darkmode state
  

dark mode

light mode

[swyxio]

@eshack94 - we are merging in this for now since its kinda working, but please feel free to update your fork and open up another PR if you have futher polish you'd like to do

(im biasing towards quicker merges and shorter lived branches)

[eshack94]

@swyxio sounds good! I've not had time to look at this in a few days due to the demands of my day-job, so I appreciate you and @seanoliver's help. I'll check out your changes and will open a new feature branch building off of it if needed!

Thanks again!