fix: bump Node.js from 20 to 22 in build-ui action

Author: Copilot

.github/actions/build-ui/action.yml

@@ -20,7 +20,7 @@ runs:
       if: steps.cache-ui.outputs.cache-hit != 'true'
       uses: actions/setup-node@v6
       with:
-        node-version: "20"
+        node-version: "22"
         cache: npm
         cache-dependency-path: ui/package-lock.json