### Background
After #9344, the Ghostty theme won't change after switching systems', and reverting #9344 will bring back the issue it fixed.
The reason these two issues are related is because the scheme change is based on changes of `effectiveAppearance`, which is also affected by setting the window's `appearance` or changing `NSAppearance.currentDrawing()`.
### Changes
Instead of observing `effectiveAppearance`, we now explicitly update the color scheme of surfaces, so that we can control when it happens to avoid callback loops and redundant updates.
### Regression Tests
- [x] #8282
- [x] Reloading with `window-theme = light` should update Ghostty with the default dark theme with a dark window theme (break before [#83104ff](83104ff27a))
- [x] `window-theme = light \n macos-titlebar-style = native` should update Ghostty with the default dark theme with a light window theme
- [x] Reloading from the default config to `theme=light:3024 Day,dark:3024 Night \n window-theme = light`, should update Ghostty with the theme `3024 Day` with a light window theme (break on [#d39cc6d](d39cc6d478))
- [x] Using `theme=light:3024 Day,dark:3024 Night`; Switching the system's appearance should change Ghostty's appearance (break on [#d39cc6d](d39cc6d478))
- [x] Reloading from `theme=light:3024 Day,dark:3024 Night` with a light window theme to the default config, should update Ghostty with the default dark theme with a dark window theme
- [x] Reloading from the default config to `theme=light:3024 Day,dark:3024 Night \n window-theme=dark`, should update Ghostty with the theme `3024 Night` with a dark window theme
- [x] Reloading from `theme=light:3024 Day,dark:3024 Night \n window-theme=dark` to `theme=light:3024 Day,dark:3024 Night` with light system appearance, should update Ghostty from dark to light
- [x] Reload with quick terminal open
# Conflicts:
# macos/Sources/Features/Terminal/BaseTerminalController.swift
Maybe fixes#8736
I thought `windowDidLoad` was early on because its before the window is
shown but apparently not. Let's try `awakeFromNib` which is called
just after the window is loaded from the nib. It is hard to get any
earlier than that.
