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/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Clusters/Drivers/GalaxyDriverPage.razor

@@ -208,7 +208,7 @@ else
     [Parameter] public string ClusterId { get; set; } = "";
     [Parameter] public string? DriverInstanceId { get; set; }
 
-    private const string DriverTypeKey = "Galaxy";
+    private const string DriverTypeKey = "GalaxyMxGateway";
 
     private bool IsNew => string.IsNullOrEmpty(DriverInstanceId);