feat(使用全局变量的 notionAPI): 避免多次创建NotionAPI，有效利用内置的concurrency并发请求限制

lib/notion/getNotionAPI.js

@@ -1,10 +1,14 @@
-import { NotionAPI } from 'notion-client'
+import { NotionAPI as NotionLibrary } from 'notion-client'
 import BLOG from '@/blog.config'
 
-export default function getNotionAPI() {
-  return new NotionAPI({
+const notionAPI = getNotionAPI()
+
+function getNotionAPI() {
+  return new NotionLibrary({
     activeUser: BLOG.NOTION_ACTIVE_USER || null,
     authToken: BLOG.NOTION_TOKEN_V2 || null,
     userTimeZone: Intl.DateTimeFormat().resolvedOptions().timeZone
   })
 }
+
+export default notionAPI