feat(undo-redo): migrate persistence from localStorage to IndexedDB

Replace inline safeStorageAdapter with indexedDBStorage. Workflow undo/
redo persistence moves from localStorage (~5MB origin cap) to IndexedDB
(~GB), eliminating QuotaExceededError that can surface from any small
persisted Zustand store (notification-storage, panel-editor-state,
etc.) once workflow-undo-redo occupies the bulk of the origin's
localStorage budget.

Same pattern as PR #2812 (terminal-console -> IndexedDB) and aligns
with PR #497's policy of minimizing localStorage usage. The earlier
safeStorageAdapter (PR #2079) silently swallowed quota throws in this
store but did not free the origin budget that the other small UI
stores share, leaving them to throw uncaught QuotaExceededError.

Fixes #4737

Signed-off-by: JaeHyung Jang <jaehyung.jang@navercorp.com>

Author: Sprexatura

apps/sim/stores/undo-redo/store.ts

@@ -3,6 +3,7 @@ import { UNDO_REDO_OPERATIONS } from '@sim/realtime-protocol/constants'
 import type { Edge } from 'reactflow'
 import { create } from 'zustand'
 import { createJSONStorage, persist } from 'zustand/middleware'
+import { indexedDBStorage } from '@/stores/undo-redo/storage'
 import type {
   BatchAddBlocksOperation,
   BatchAddEdgesOperation,
@@ -47,41 +48,6 @@ function getStackKey(workflowId: string, userId: string): string {
   return `${workflowId}:${userId}`
 }
 
-/**
- * Custom storage adapter for Zustand's persist middleware.
- * We need this wrapper to gracefully handle 'QuotaExceededError' when localStorage is full,
- * Without this, the default storage engine would throw and crash the application.
- * and to properly handle SSR/Node.js environments.
- */
-const safeStorageAdapter = {
-  getItem: (name: string): string | null => {
-    if (typeof localStorage === 'undefined') return null
-    try {
-      return localStorage.getItem(name)
-    } catch (e) {
-      logger.warn('Failed to read from localStorage', e)
-      return null
-    }
-  },
-  setItem: (name: string, value: string): void => {
-    if (typeof localStorage === 'undefined') return
-    try {
-      localStorage.setItem(name, value)
-    } catch (e) {
-      // Log warning but don't crash - this handles QuotaExceededError
-      logger.warn('Failed to save to localStorage', e)
-    }
-  },
-  removeItem: (name: string): void => {
-    if (typeof localStorage === 'undefined') return
-    try {
-      localStorage.removeItem(name)
-    } catch (e) {
-      logger.warn('Failed to remove from localStorage', e)
-    }
-  },
-}
-
 function isOperationApplicable(
   operation: Operation,
   graph: { blocksById: Record<string, BlockState>; edgesById: Record<string, Edge> }
@@ -501,7 +467,7 @@ export const useUndoRedoStore = create<UndoRedoState>()(
     }),
     {
       name: 'workflow-undo-redo',
-      storage: createJSONStorage(() => safeStorageAdapter),
+      storage: createJSONStorage(() => indexedDBStorage),
       partialize: (state) => ({
         stacks: state.stacks,
         capacity: state.capacity,