Add Phase 1 proxy auth howtos and sidebar - Howto-Authelia-proxy-auth.md: step-by-step for Traefik+Authelia, Caddy, nginx variants - Howto-Authentik-proxy-auth.md: step-by-step for Authentik embedded outpost with Caddy/Traefik - Howto-Troubleshoot-proxy-login.md: 7-step diagnostic guide for stuck proxy logins - _Sidebar.md: new wiki sidebar surfacing all pages - Home.md: How-to guides section with Phase 1 proxy auth entries - Troubleshooting.md: proxy SSO, OIDC, multi-user sections (from earlier work) - Reverse-proxy-and-SSO.md: updated SSO section to reference proxy auth mode