refactor: align TenantRepository with CleanDDD/NetCorePal规范

- remove duplicate ITenantRepository/TenantRepository from Console
- extend Platform ITenantRepository with GetByIdAsync, GetPagedAsync, CountAsync
- update Console services to use Platform.Infrastructure.Repositories
- fix nullable warnings (UserDto, OAuthClientService)
- fix YarpGateway Directory.Build.props duplicate import
- fix DynamicProxyConfigProvider CS8618 warning

Directory.Build.props

@@ -1,7 +1,4 @@
 <Project>
-  <!-- Import central package management from parent directory -->
-  <Import Project="$(MSBuildThisFileDirectory)../Directory.Packages.props" Condition="Exists('$(MSBuildThisFileDirectory)../Directory.Packages.props')" />
-  
   <PropertyGroup>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>

DynamicProxy/DynamicProxyConfigProvider.cs

@@ -19,6 +19,7 @@ public class DynamicProxyConfigProvider : IProxyConfigProvider
         _routeProvider = routeProvider;
         _clusterProvider = clusterProvider;
         _cts = new CancellationTokenSource();
+        _config = null!;
         UpdateConfig();
     }