Keep desktop browser tabs stable across focus and automation (#2907)

* fix(desktop): preserve browser tabs across focus changes

Electron can replace a guest WebContents when a webview is reparented, which reloads the page and can race automation against a destroyed target. Keep each browser guest on one permanent paintable surface and make user and agent resizing share one canonical viewport.

* fix(desktop): recover browser surfaces after lifecycle changes

* fix(desktop): preserve resident browser lifecycle state

* fix(desktop): seed inactive browser viewport

packages/app/src/desktop/browser/automation/handler.ts

@@ -5,7 +5,12 @@ import {
   removeResidentBrowserWebview,
   resizeResidentBrowserWebview,
 } from "@/desktop/browser/resident-webviews";
-import { createWorkspaceBrowser, getBrowserRecord, useBrowserStore } from "@/desktop/browser/store";
+import {
+  createFixedBrowserViewport,
+  createWorkspaceBrowser,
+  getBrowserRecord,
+  useBrowserStore,
+} from "@/desktop/browser/store";
 import { collectAllTabs, useWorkspaceLayoutStore } from "@/stores/workspace-layout-store";
 import { buildWorkspaceTabPersistenceKey } from "@/workspace-tabs/model";
 
@@ -208,6 +213,9 @@ function resizeBrowserTabForRequest(params: {
       message: `No browser tab found for ID: ${browserId}`,
     });
   }
+  useBrowserStore
+    .getState()
+    .setBrowserViewport(browserId, createFixedBrowserViewport(dimensions.width, dimensions.height));
 
   return {
     requestId: request.requestId,