Добить структуру Api, Contracts, SharedKernel и сервисов

Deal.Api/Http -> Services/Models/Extensions; Contracts/Integrations
и SharedKernel/Tenants -> Abstractions/Models; extension-классы
telegram/ml -> Extensions. namespace/using/FQN мигрированы, using
дедуплицированы.

src/core/Deal.Api/Endpoints/EventsEndpoint.cs

@@ -1,5 +1,6 @@
 using Deal.Api.Events;
-using Deal.Api.Http;
+using Deal.Api.Extensions;
+using Deal.Api.Models;
 using Deal.Api.Services;
 using Deal.Api.Dtos;