review(Security): fix login open-redirect (High) + stale LDAP doc

Code review at HEAD 7286d320. Security-001 (High): guard returnUrl with a local-URL
check before redirect (open-redirect/phishing vector) + regression test. Security-002:
update stale LdapOptions dev-LDAP doc reference.

src/Server/ZB.MOM.WW.OtOpcUa.Security/Ldap/LdapOptions.cs

@@ -5,8 +5,9 @@ namespace ZB.MOM.WW.OtOpcUa.Security.Ldap;
 
 /// <summary>
 ///     LDAP + role-mapping configuration for the Admin UI. Bound from <c>appsettings.json</c>
-///     <c>Security:Ldap</c> section. Defaults point at the local GLAuth dev instance (see
-///     <c>C:\publish\glauth\auth.md</c>).
+///     <c>Security:Ldap</c> section. Defaults point at the shared GLAuth dev instance on the
+///     Linux Docker host (<c>10.100.0.35:3893</c>) — see <c>docs/security.md</c> §"LDAP bind
+///     flow" and <c>CLAUDE.md</c> §"LDAP Authentication" for setup details.
 /// </summary>
 /// <remarks>
 ///     Carries both the wire fields the shared <c>ZB.MOM.WW.Auth.Ldap</c> directory client needs