Whitelist & temp disable blocking for unprivileged clients

One major problem with DNS-based adblockers is that unprivileged clients have no way to whitelist or disable adblocking to fix page damage on their own. This responsibility all falls to the server admin, unless they give admin access to everybody.

Since AG Home has the ability to set DNS on a per-client basis, it should be possible to fix that. This would be a _killer_ feature differentiating AGH from Pihole. My thoughts are:

1) Client goes to "https://adguard". Ideally this would be a configurable local hostname that always works. This page is separate from the full admin site with limited privileges.

If parental control is off, this site is accessible without any authentication. Otherwise it requires a password shared between all (adult) clients.

2) The (adult) client is permitted to white/blacklist hosts and/or disable blocking for a configurable period of time, all affecting that client only. Per-client configurations persist and are saved by MAC address.

3) That's it!