perf(stores): defer safeStorage writes off the interaction path (#1941)

* perf(stores): defer safeStorage writes off the interaction path

Session switches funnel every persisted store slice through safeStorage.setItem,
and doing those large JSON.stringify writes synchronously blocked the main
thread for over a second. Add a write-behind buffer that:

- Defers each setItem/removeItem to a later task via setTimeout(0) so the
  click-to-paint path is not blocked.
- Coalesces repeated writes to the same key into a single backing flush.
- Serves pending values from memory so read-after-write stays consistent
  within the deferral window.
- Flushes synchronously on pagehide/beforeunload/visibilitychange/freeze so
  deferred state survives tab close, reload, and the mobile freeze lifecycle.

Adds a test covering write deferral, coalescing, and pending read serving.

* fix(stores): defer persisted JSON serialization

* fix(stores): defer direct safeStorage writes

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/hooks/usePwaInstallPrompt.ts

@@ -3,7 +3,7 @@ import { toast } from '@/components/ui';
 import { isWebRuntime } from '@/lib/desktop';
 import { usePwaDetection } from '@/hooks/usePwaDetection';
 import { useI18n } from '@/lib/i18n';
-import { getSafeSessionStorage, getSafeStorage } from '@/stores/utils/safeStorage';
+import { getDeferredSafeStorage, getSafeSessionStorage } from '@/stores/utils/safeStorage';
 import { shouldShowPwaInstallToast } from '@/components/update/openCodeUpdateDedup';
 
 type InstallPromptOutcome = 'accepted' | 'dismissed';
@@ -66,7 +66,7 @@ export const usePwaInstallPrompt = () => {
       installEvent.preventDefault();
       deferredPrompt = installEvent;
 
-      const localStorage = getSafeStorage();
+      const localStorage = getDeferredSafeStorage();
       const sessionStorage = getSafeSessionStorage();
       const decision = shouldShowPwaInstallToast({
         dismissed: localStorage.getItem(INSTALL_TOAST_DISMISSED_KEY),
@@ -90,7 +90,7 @@ export const usePwaInstallPrompt = () => {
         cancel: {
           label: tRef.current('pwa.installPrompt.dismiss'),
           onClick: () => {
-            getSafeStorage().setItem(INSTALL_TOAST_DISMISSED_KEY, 'true');
+            getDeferredSafeStorage().setItem(INSTALL_TOAST_DISMISSED_KEY, 'true');
             dismissInstallToast();
           },
         },