Remove incorrect [Flags] attribute from EnterpriseAttestationType

The enum values (None=0, VendorFacilitated=1, PlatformManaged=2) are
mutually exclusive attestation levels per the FIDO spec, not combinable
bit flags.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Src/DSInternals.Win32.WebAuthn/Enums/EnterpriseAttestationType.cs

@@ -1,5 +1,4 @@
-using System;
-using Windows.Win32;
+using Windows.Win32;
 
 namespace DSInternals.Win32.WebAuthn
 {
@@ -7,7 +6,6 @@ namespace DSInternals.Win32.WebAuthn
     /// Enterprise Attestation Capabilities
     /// </summary>
     /// <see>https://fidoalliance.org/specs/fido-v2.1-rd-20201208/fido-client-to-authenticator-protocol-v2.1-rd-20201208.html#sctn-feature-descriptions-enterp-attstn</see>
-    [Flags]
     public enum EnterpriseAttestationType : uint
     {
         /// <remarks>