update(examples): Add Provider example

* Provider example shows usage of store outside of Flow

examples/Provider/Sidebar.vue

@@ -0,0 +1,27 @@
+<script lang="ts" setup>
+import { useStore } from '~/index'
+const store = useStore()
+
+const nodes = computed(() => store.nodes)
+const transform = computed(() => store.transform)
+
+const selectAll = () => {
+  store.selectedElements = nodes.value
+  store.unsetUserSelection()
+}
+</script>
+<template>
+  <aside>
+    <div class="description">This is an example of how you can access the internal state outside of the ReactFlow component.</div>
+    <div class="title">Zoom & pan transform</div>
+    <div class="transform">{{ [transform[0].toFixed(2), transform[1].toFixed(2), transform[2].toFixed(2)] }}</div>
+    <div class="title">Nodes</div>
+    <div v-for="node of nodes" :key="node.id">
+      Node {{ node.id }} - x: {{ node.__rf.position.x.toFixed(2) }}, y: {{ node.__rf.position.y.toFixed(2) }}
+    </div>
+
+    <div class="selectall">
+      <button @click="selectAll">select all nodes</button>
+    </div>
+  </aside>
+</template>