feat(ci): create artifact with nixin website

.forgejo/workflows/artifact.yaml

@@ -0,0 +1,24 @@
+name: "create artifact with nixin's website"
+on:
+  push:
+    branches:
+      - prod
+jobs:
+  build:
+    name: Create artifact
+    runs-on: debian-latest
+    steps:
+      - name: checkout repository
+        uses: actions/checkout@v4
+      - name: show what we get
+        run: ls -l
+      - name: npm ci
+        run: npm ci
+      - name: vitepress build
+        run: npm run docs:build
+      - name: create artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: nixin-website
+          path: |
+            .vitepress/dist