Notify of changed site files on ZeroHello.

I would like to be notified ASAP of changed files. ZeroHello's owned sites list is a perfect location for it.

Start by locating the ZeroHello owned sites list and the code that represents site files. Determine how changed files can be detected and how notifications should be presented. Done means users are notified promptly when files change, but the issue does not specify the detection or notification behavior.

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