fix(host,security): wire static assets, DI lifetimes, form login, dev-stub LDAP

Six interlocking fixes surfaced while smoke-testing the fused Host in a browser:

- Host/Program.cs: UseStaticWebAssets() opts into the RCL static-asset pipeline
  in any environment (auto-only in Development), MapStaticAssets().AllowAnonymous()
  exempts CSS/JS from the AddOtOpcUaAuth fallback policy, and
  AddCascadingAuthenticationState() lets <AuthorizeView/> work inside interactive
  components (NavSidebar's session block).
- Security/ServiceCollectionExtensions: ILdapAuthService Scoped → Singleton —
  consumed by the Singleton LdapOpcUaUserAuthenticator on driver-role nodes.
  Crash only surfaced in Development (ValidateOnBuild=true).
- Security/Endpoints/AuthEndpoints: /auth/login now dispatches on Content-Type —
  application/json keeps the original 204/401/503 contract for tests, and
  application/x-www-form-urlencoded (the browser <form>) gets a redirect dance.
  DisableAntiforgery on the login endpoint (it's the entry point, no prior session)
  and AllowAnonymous to override the fallback policy.
- Security/Ldap/LdapOptions + LdapAuthService: real DevStubMode property; when
  true the auth service bypasses the LDAP bind and returns a FleetAdmin role so
  dev/test can navigate the full Admin UI without GLAuth running.
- AdminUI/EndpointRouteBuilderExtensions: doc-comment update about static-asset
  flow (the actual MapStaticAssets call lives in Host/Program.cs).

src/Server/ZB.MOM.WW.OtOpcUa.Security/ServiceCollectionExtensions.cs

@@ -43,7 +43,11 @@ public static class ServiceCollectionExtensions
         services.AddOptions<LdapOptions>().Bind(configuration.GetSection(LdapOptions.SectionName));
 
         services.AddSingleton<JwtTokenService>();
-        services.AddScoped<ILdapAuthService, LdapAuthService>();
+        // Singleton — LdapAuthService is stateless (creates an LdapConnection per call) and
+        // must be consumable by the Singleton LdapOpcUaUserAuthenticator on driver-role nodes.
+        // The driver-branch in Host/Program.cs registers the same way; consistent lifetime
+        // across both paths keeps ValidateScopes-on-Build clean.
+        services.AddSingleton<ILdapAuthService, LdapAuthService>();
 
         services.AddDataProtection()
             .PersistKeysToDbContext<OtOpcUaConfigDbContext>()