Consider adding a philter debug/audit mode

[mikix]

We are considering adding built-in philter support (#77). Inevitably that support will probably be allow-listed or block-listed in some fashion.

Another thought is to additionally add an "audit" mode where we run philter on everything unconditionally, and report on any differences. So like, let's say we only run philter on notes. The audit mode could run it on every string field anywhere, or the raw json maybe. And report on anything it caught over and above our normal mode.

This way, we could periodically test whether we should be philtering even more.