macos: explicitly free surface resource on split/tab close

We don't wait for Swift to garbage collect. We just free the expensive
stuff (our surface) immediately.

macos/Sources/Ghostty/Ghostty.SplitView.swift

@@ -45,6 +45,23 @@ extension Ghostty {
             }
         }
         
+        /// Close the surface associated with this node. This will likely deinitialize the
+        /// surface. At this point, the surface view in this node tree can never be used again.
+        func close() {
+            switch (self) {
+            case .noSplit(let leaf):
+                leaf.surface.close()
+                
+            case .horizontal(let container):
+                container.topLeft.close()
+                container.bottomRight.close()
+                
+            case .vertical(let container):
+                container.topLeft.close()
+                container.bottomRight.close()
+            }
+        }
+        
         class Leaf: ObservableObject {
             let app: ghostty_app_t
             @Published var surface: SurfaceView
@@ -144,6 +161,11 @@ extension Ghostty {
                     )
                     .onChange(of: requestClose) { value in
                         guard value else { return }
+                        
+                        // Free any resources associated with this root, we're closing.
+                        node.close()
+                        
+                        // Call our callback
                         guard let onClose = self.onClose else { return }
                         onClose()
                     }
@@ -289,6 +311,9 @@ extension Ghostty {
                 .onChange(of: closeTopLeft) { value in
                     guard value else { return }
                     
+                    // Close the top left and release all resources
+                    container.topLeft.close()
+                    
                     // When closing the topLeft, our parent becomes the bottomRight.
                     node = container.bottomRight
                     TerminalSplitLeaf.moveFocus(node, previous: container.topLeft)
@@ -307,6 +332,9 @@ extension Ghostty {
                 .onChange(of: closeBottomRight) { value in
                     guard value else { return }
                     
+                    // Close the node and release all resources
+                    container.bottomRight.close()
+                    
                     // When closing the bottomRight, our parent becomes the topLeft.
                     node = container.topLeft
                     TerminalSplitLeaf.moveFocus(node, previous: container.bottomRight)

macos/Sources/Ghostty/SurfaceView.swift

@@ -153,6 +153,16 @@ extension Ghostty {
             ghostty_surface_free(surface)
         }
         
+        /// Close the surface early. This will free the associated Ghostty surface and the view will
+        /// no longer render. The view can never be used again. This is a way for us to free the
+        /// Ghostty resources while references may still be held to this view. I've found that SwiftUI
+        /// tends to hold this view longer than it should so we free the expensive stuff explicitly.
+        func close() {
+            guard let surface = self.surface else { return }
+            ghostty_surface_free(surface)
+            self.surface = nil
+        }
+        
         func focusDidChange(_ focused: Bool) {
             guard let surface = self.surface else { return }
             ghostty_surface_set_focus(surface, focused)