Proxy your Selenium tests through ZAP and then use ZAP to test your app.
Exploring apps effectively is always a challenge for automated scanners, but a good set of Selenium tests are a great way to teach a scanner like ZAP about how your app works. You can either not bother using the ZAP Spiders or just use them to catch areas of you app that dont have enough tests. By proxying your tests via ZAP you will automatically get passive scanning, and once they have finnished you can use active scanning to run the more agressive attacks.
ZAP has a very powerful API so can be completely automated for this sort of testing.