feat: use v-html for node labels

* add span tag as wrapper for node labels

feat(examples):

* Add overview example

examples/NodeTypeChange/NodeTypeChangeExample.vue

@@ -0,0 +1,45 @@
+<script lang="ts" setup>
+import { CSSProperties } from 'vue'
+import Flow, { addEdge, Connection, Elements, OnLoadParams, Position, Edge, isEdge } from '~/index'
+
+const onLoad = (reactFlowInstance: OnLoadParams) => reactFlowInstance.fitView()
+
+const initialElements: Elements = [
+  {
+    id: '1',
+    sourcePosition: Position.Right,
+    type: 'input',
+    data: { label: 'Input' },
+    position: { x: 0, y: 80 },
+  },
+  {
+    id: '2',
+    type: 'output',
+    sourcePosition: Position.Right,
+    targetPosition: Position.Left,
+    data: { label: 'A Node' },
+    position: { x: 250, y: 0 },
+  },
+  { id: 'e1-2', source: '1', type: 'smoothstep', target: '2', animated: true },
+] as Elements
+
+const buttonStyle: CSSProperties = { position: 'absolute', right: 10, top: 30, zIndex: 4 }
+
+const elements = ref<Elements>(initialElements)
+const onConnect = (params: Connection | Edge) => (elements.value = addEdge(params, elements.value))
+const changeType = () => {
+  elements.value = elements.value.map((el) => {
+    if (isEdge(el) || el.type === 'input') return el
+
+    return {
+      ...el,
+      type: el.type === 'default' ? 'output' : 'default',
+    }
+  })
+}
+</script>
+<template>
+  <Flow :elements="elements" @connect="onConnect" @load="onLoad">
+    <button :style="buttonStyle" @click="changeType">change type</button>
+  </Flow>
+</template>