update(examples): Add Save & Restore example

* add localforage to dev deps

examples/SaveRestore/SaveRestoreExample.vue

@@ -0,0 +1,26 @@
+<script lang="ts" setup>
+import Controls from './Controls.vue'
+import Flow, { addEdge, Connection, Node, Edge, Elements, OnLoadParams, removeElements } from '~/index'
+
+import './save.css'
+
+const initialElements: Elements = [
+  { id: '1', data: { label: 'Node 1' }, position: { x: 100, y: 100 } },
+  { id: '2', data: { label: 'Node 2' }, position: { x: 100, y: 200 } },
+  { id: 'e1-2', source: '1', target: '2' },
+] as Elements
+
+const elements = ref(initialElements)
+const flowInstance = ref()
+
+const onConnect = (params: Connection | Edge) => (elements.value = addEdge(params, elements.value))
+const onElementsRemove = (elementsToRemove: Elements) => (elements.value = removeElements(elementsToRemove, elements.value))
+const onLoad = (instance: OnLoadParams) => (flowInstance.value = instance)
+const onRestore = (els: Elements) => (elements.value = els)
+const onAdd = (el: Node) => (elements.value = elements.value.concat(el))
+</script>
+<template>
+  <Flow :elements="elements" @elements-remove="onElementsRemove" @connect="onConnect" @load="onLoad">
+    <Controls :flow-instance="flowInstance" @restore="onRestore" @add="onAdd" />
+  </Flow>
+</template>