build UI in workflow

Author: samfreund

.github/workflows/build.yml

@@ -91,6 +91,8 @@ jobs:
         run: |
           pnpm install
           pnpm exec playwright install --with-deps
+      - name: Build UI
+        run: ./gradlew buildAndCopyUI
       - name: Run Playwright tests
         working-directory: photon-client
         run: pnpm exec playwright test