fix(galaxy): complete PR 7.2 rename — use canonical GalaxyMxGateway driver type

The driver/factory/seed use 'GalaxyMxGateway' (legacy 'Galaxy' was retired),
but the AdminUI editor router, GalaxyDriverPage, address picker, identity
dropdown, the Galaxy browser/probe, and DraftValidator still keyed on 'Galaxy'.
Result: the seeded GalaxyMxGateway driver couldn't be edited ('no editor
registered'), UI-created Galaxy drivers wrote a type with no factory, and a
SystemPlatform-bound GalaxyMxGateway driver failed publish validation.
Align all stragglers to GalaxyMxGateway (+ failing-test-first DraftValidator
coverage). ShouldStub's 'Galaxy' legacy safety-net left intact.

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Validation/DraftValidator.cs

@@ -172,8 +172,8 @@ public static class DraftValidator
 
             var compat = ns.Kind switch
             {
-                NamespaceKind.SystemPlatform => di.DriverType == "Galaxy",
-                NamespaceKind.Equipment      => di.DriverType != "Galaxy",
+                NamespaceKind.SystemPlatform => di.DriverType == "GalaxyMxGateway",
+                NamespaceKind.Equipment      => di.DriverType != "GalaxyMxGateway",
                 _                            => true,
             };