xdg-activation: fix race with transaction system

This code could allows the view to be focused and urgent at the
same time if the request to activate the view is received just after
the pending focus has been set but before the transaction completes.

river/Server.zig

@@ -289,7 +289,7 @@ fn handleRequestActivate(
 
     const node_data = SceneNodeData.fromSurface(event.surface) orelse return;
     switch (node_data.data) {
-        .view => |view| if (view.current.focus == 0) {
+        .view => |view| if (view.pending.focus == 0) {
             view.pending.urgent = true;
             server.root.applyPending();
         },