macos: sync appearance when new windows are created (#13675)

For new windows to get their appearance synced, we need to call
`syncAppearance` after `super.showWindow(sender)`. All previous calls to
`syncAppearance` on `TerminalWindow` will be ignored because the window
needs to have `isVisible` set to `true`.

This regression was introduced by:
5368adcd29

It added `.dropFirst()` to the `focusedSurface` appearance publishers in
`TerminalController.swift` which removes the initial call of the
subscription.

Fixes https://github.com/ghostty-org/ghostty/issues/13324

(landed on the same fix as @rasitakyol found here:
https://github.com/ghostty-org/ghostty/pull/13341)

macos/Sources/Features/Terminal/TerminalController.swift

@@ -1160,6 +1160,8 @@ class TerminalController: BaseTerminalController, TabGroupCloseCoordinator.Contr
         }
 
         super.showWindow(sender)
+
+        syncAppearance()
     }
 
     // Shows the "+" button in the tab bar, responds to that click.