domain verification state changes should purge website cache

this is unrelated to ongoing dns verification instability that was cited on bsky. it happened again and I was able to verify after a while but https://atvouch.dev was inconsistent depending on source IP. I think I was able to trigger a cache purge by re-uploading the website but not fully sure

(note: don't actually know the architecture to truly know if it's some caching or not)