macOS: fix first responder after dragging a non-focused surface

This fixes a bug: after dragging a non-focused surface from window A to window B **quickly without making B the key window**, the focused surface in window A is not receiving `keyDown` events.

Author: bo2themax

macos/Sources/Features/Terminal/BaseTerminalController.swift

@@ -458,8 +458,12 @@ class BaseTerminalController: NSWindowController,
 
         replaceSurfaceTree(
             surfaceTree.removing(node),
-            moveFocusTo: nextFocus,
-            moveFocusFrom: focusedSurface,
+            // When a non-focused surface is removed and this window stays as the key window,
+            // we should refocus the `focusedSurface` to make sure the window's firstResponder remains as it is.
+            //
+            // This is a weird workaround, since `resignFirstResponder` wasn't called on `focusedSurface` after drag,
+            // but the first responder became the window itself.
+            moveFocusTo: nextFocus ?? focusedSurface,
             undoAction: "Close Terminal"
         )
     }