build(host): declare ZB.MOM.WW.Theme directly (not transitively via CentralUI)

Host/App.razor uses the kit's <ThemeHead/>/<ThemeScripts/>, but Host had no direct
PackageReference — it relied on CentralUI re-exporting the package transitively.
Add a versionless <PackageReference Include="ZB.MOM.WW.Theme"/> (version pinned by
central PM at Directory.Packages.props) so the declared dependency matches actual
usage and survives any future PrivateAssets/refactor on CentralUI. Additive only;
Host builds clean (0/0).

src/ZB.MOM.WW.ScadaBridge.Host/ZB.MOM.WW.ScadaBridge.Host.csproj

@@ -34,6 +34,9 @@
     <PackageReference Include="ZB.MOM.WW.Health.EntityFrameworkCore" />
     <PackageReference Include="ZB.MOM.WW.Telemetry" />
     <PackageReference Include="ZB.MOM.WW.Telemetry.Serilog" />
+    <!-- Host/App.razor uses the kit's <ThemeHead/>/<ThemeScripts/> directly; declare the
+         dependency here rather than leaning on CentralUI re-exporting it transitively. -->
+    <PackageReference Include="ZB.MOM.WW.Theme" />
   </ItemGroup>
 
   <ItemGroup>