Dashboard: replace inline fully-qualified type refs with @using

ApiKeysPage and GalaxyPage referenced ApiKeyConstraints and
GalaxyRepositoryOptions by full namespace inside @code. Add the
appropriate @using directive at the top of each file and let the
short type names resolve through that.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.MxGateway.Server/Dashboard/Components/Pages/GalaxyPage.razor

@@ -1,5 +1,6 @@
 @page "/galaxy"
 @inherits DashboardPageBase
+@using ZB.MOM.WW.MxGateway.Server.Galaxy
 
 <PageTitle>Dashboard Galaxy</PageTitle>
 
@@ -140,7 +141,7 @@ else
 
 @code {
     [Inject]
-    private IOptions<ZB.MOM.WW.MxGateway.Server.Galaxy.GalaxyRepositoryOptions> GalaxyOptions { get; set; } = null!;
+    private IOptions<GalaxyRepositoryOptions> GalaxyOptions { get; set; } = null!;
 
     private string RefreshHeading()
     {