Use StyleDark as default theme (and unset some of the defaults in palette etc)

[rhodes-b]

mbadolato/iTerm2-Color-Schemes#520

This was recently merged into the color schemes repo. Which takes the default baked in palette from the ghostty config.
I think it makes sense to set this as the default theme since I have seen quite a few people ask what it is and the best answer before was to grep the default config for all the palette options which is not as nice.

This can also help with a conflict if people copy some of the default config where it seems like theme wont apply because the palette options override their theme selection

[rhodes-b]

Id be willing to do this, I just wanted to make a discussion first in case the answer was no

[mitchellh]

Loading a theme makes the startup slower because we have to (1) read an additional file and (2) reload the config (implementation detail). For these reasons, I'd rather not since even though its likely nanoseconds, it impacts that first user experience which is extremely important.

I see your arguments though. Perhaps we can compromise with a docs change?

[rhodes-b]

Likewise I can see your arguments, I think something on the docs site works just fine as a solution