fix(ci): pin node runtime for frontend vitest compatibility

.gitea/workflows/ci.yml

@@ -71,6 +71,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20.x'
+
       - name: Setup Bun
         uses: oven-sh/setup-bun@v2
         with: