Basically a toggle for #43 because some users/modpacks may prefer that.

I tried to investigate that code to make a PR but didn't really understand where you actually remove a server from whitelist upon successful check, so I gave up for now.

They are never removed from whitelist. Server safety status is updated after successful login, with respect to data gathered during login process: https://github.com/Aizistral-Studios/No-Chat-Reports/blob/1.19.1-Fabric-Port/src/main/java/com/aizistral/nochatreports/NoChatReportsClient.java#L101-L105

Whitelisting a server basically makes it so that mod skips the step with warning screen and operates as if user clicked "Proceed". If there is no warning screen (i.e. server doesn't have enforce-secure-profile enabled) - it doesn't do anything. Server will remain in the whitelist, but it will only matter if it's configuration changes in the future.