feat(electron): electron shell skeleton (#8127)

fix AF-1331
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missing
- per split view skeleton
- per route skeleton

packages/frontend/mobile/src/app.tsx

@@ -81,7 +81,7 @@ export function App() {
         <AffineContext store={getCurrentStore()}>
           <Telemetry />
           <RouterProvider
-            fallbackElement={<AppFallback key="RouterFallback" />}
+            fallbackElement={<AppFallback />}
             router={router}
             future={future}
           />

packages/frontend/mobile/src/pages/workspace/layout.tsx

@@ -70,7 +70,7 @@ export const WorkspaceLayout = ({
   if (!isRootDocReady) {
     return (
       <FrameworkScope scope={workspace.scope}>
-        <AppFallback key="workspaceLoading" />
+        <AppFallback />
       </FrameworkScope>
     );
   }