Add GitHub Pages

Not replacing Netlify, but easier to see if build fails or not quickly.

.github/workflows/deploy.yml

@@ -0,0 +1,34 @@
+name: Deploy
+on:
+    workflow_dispatch: {}
+    push:
+        branches:
+            - v3-vitepress
+jobs:
+    deploy:
+        runs-on: ubuntu-latest
+        permissions:
+            contents: read
+            pages: write
+            id-token: write
+        environment:
+            name: github-pages
+            url: ${{ steps.deployment.outputs.page_url }}
+        steps:
+            - uses: actions/checkout@v3
+              with:
+                  fetch-depth: 0
+            - uses: actions/setup-node@v3
+              with:
+                  node-version: 16
+                  cache: npm
+            - run: npm ci
+            - name: Build
+              run: npm run docs:build
+            - uses: actions/configure-pages@v2
+            - uses: actions/upload-pages-artifact@v1
+              with:
+                  path: src/.vitepress/dist
+            - name: Deploy
+              id: deployment
+              uses: actions/deploy-pages@v1