Update @zen-browser/surfer to version 1.4.12

Refactor build/winsign/sign.ps1 to download windows-x64-obj-generic
Update subproject commit reference
Fix sidebar flashing issue when in split view mode

src/browser/base/content/ZenUIManager.mjs

@@ -169,7 +169,8 @@ var gZenCompactModeManager = {
 
   flashSidebar() {
     let sidebar = document.getElementById('navigator-toolbox');
-    if (sidebar.matches(':hover')) {
+    let tabPanels = document.getElementById('tabbrowser-tabpanels');
+    if (sidebar.matches(':hover') || tabPanels.matches("[zen-split-view='true']")) {
       return;
     }
     if (this._flashSidebarTimeout) {