chore: add surge preview action (#7042)

https://github.com/marketplace/actions/surge-pr-preview

.github/workflows/preview.yml

@@ -0,0 +1,19 @@
+name: 🔂 Surge PR Preview
+
+on: [push, pull_request]
+
+jobs:
+  preview:
+    runs-on: ubuntu-latest
+    env:
+      PUBLIC_PATH: '/'
+    steps:
+      - uses: actions/checkout@v2
+      - uses: afc163/surge-preview@v1
+        with:
+          surge_token: ${{ secrets.SURGE_TOKEN }}
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          build: |
+            npm install
+            ./node_modules/.bin/vant-cli build-site
+          dist: site

vant.config.js

@@ -3,7 +3,7 @@ module.exports = {
   build: {
     skipInstall: ['lazyload'],
     site: {
-      publicPath: 'https://b.yzcdn.cn/vant/',
+      publicPath: process.env.PUBLIC_PATH || 'https://b.yzcdn.cn/vant/',
     },
     vetur: {
       tagPrefix: 'van-',