Add Node.js setup and UI build steps to CI workflow

- Added a step to set up Node.js version 20 in the CI workflow.
- Included installation of UI dependencies and a build step for UI assets.
- Enhanced the CI process to ensure UI components are built before running tests.

.gitea/workflows/ci.yaml

@@ -20,6 +20,19 @@ jobs:
           go-version-file: go.mod
           cache: true
 
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+          cache: npm
+          cache-dependency-path: web/ui/package-lock.json
+
+      - name: Install UI deps
+        run: npm --prefix ./web/ui ci
+
+      - name: Build UI assets
+        run: npm --prefix ./web/ui run build
+
       - name: Run tests
         run: make test