macOS: move surface to OSSurfaceView

macos/Sources/Ghostty/Surface View/OSSurfaceView.swift

@@ -48,6 +48,10 @@ extension Ghostty {
         /// True when the surface should show a highlight effect (e.g., when presented via goto_split).
         @Published private(set) var highlighted: Bool = false
 
+        var surface: ghostty_surface_t? {
+            nil
+        }
+
         init(id: UUID?, frame: CGRect) {
             self.id = id ?? UUID()
             super.init(frame: frame)

macos/Sources/Ghostty/Surface View/SurfaceView_AppKit.swift

@@ -164,7 +164,7 @@ extension Ghostty {
         private(set) var surfaceModel: Ghostty.Surface?
 
         /// Returns the underlying C value for the surface. See "note" on surfaceModel.
-        var surface: ghostty_surface_t? {
+        override var surface: ghostty_surface_t? {
             surfaceModel?.unsafeCValue
         }
         /// Current scrollbar state, cached here for persistence across rebuilds

macos/Sources/Ghostty/Surface View/SurfaceView_UIKit.swift

@@ -14,7 +14,11 @@ extension Ghostty {
         // The current search state. When non-nil, the search overlay should be shown.
         @Published var searchState: SearchState?
 
-        private(set) var surface: ghostty_surface_t?
+        private(set) var _surface: ghostty_surface_t?
+
+        override var surface: ghostty_surface_t? {
+            _surface
+        }
 
         init(_ app: ghostty_app_t, baseConfig: SurfaceConfiguration? = nil, uuid: UUID? = nil) {
 
@@ -32,7 +36,7 @@ extension Ghostty {
                 // TODO
                 return
             }
-            self.surface = surface
+            self._surface = surface
         }
 
         required init?(coder: NSCoder) {