✅(frontend) add e2e tests for SDK picker selection

Cover the two main picker outcomes: cancelling leaves the item
private, and confirming exposes a publicly reachable URL. The
reach check opens the returned URL in a fresh anonymous context
and waits for the download event, since the backend serves
attachments with Content-Disposition and navigation aborts.

To run the test in CI, build the drive SDK package and start the
sdk-consumer dev server before the playwright job.

.github/workflows/drive-frontend.yml

@@ -161,6 +161,17 @@ jobs:
           cd src/frontend/apps/e2e
           npx playwright install-deps ${{ matrix.browser }}
 
+      - name: Build the drive SDK
+        run: |
+          cd src/frontend/packages/sdk
+          yarn build
+
+      - name: Start sdk-consumer dev server
+        run: |
+          cd src/frontend/apps/sdk-consumer
+          nohup yarn dev > /tmp/sdk-consumer.log 2>&1 &
+          echo "sdk-consumer PID $!"
+
       - name: Download frontend bundle
         uses: actions/download-artifact@v4
         with: