How can Cloudflare Zero Trust policies be leveraged to add an extra layer of authentication and access control to a WireGuard VPN routed through a Cloudflare Tunnel?

Cloudflare Zero Trust policies can be leveraged by creating an Application (type 'Self-hosted') for the tunnel's hostname (e.g., `vpn.yourdomain.com`). Within this application, you can define access policies that require users to authenticate via an identity provider (IdP) like Google, Okta, Azure AD, etc., before `cloudflared` will even forward their traffic to the WireGuard server. This adds multi-factor authentication and granular access control (e.g., based on email, group membership, device posture) that must be satisfied *before* the WireGuard handshake can even begin, significantly enhancing the security posture of the VPN access.