This fixes two overlapping issues regarding window positioning and Cmd+W window closures on macOS:
1. `window-position-x` and `window-position-y` coordinates were being ignored on initial launch because `TerminalWindow.setInitialWindowPosition` depended on the `TerminalController`, which isn't fully attached during `awakeFromNib`. This logic was moved so explicit coordinates are correctly enforced.
2. When closing a window via Cmd+W (leaving the app active), reopening the window would continuously cascade down and to the right rather than restoring to the previous position. It now checks if there are other windows open before cascading.
3. `LastWindowPosition` was updated to save both the frame origin and size (width/height), ensuring that restoring a closed window correctly mimics native AppKit State Restoration size behaviors while honoring explicit configurations.
### 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
