Add private chat support and group model enhancements

Introduces repositories, validators, and integration tests for private chats. Refactors group-related models to support invitations and memberships, updates group repository interfaces and implementations, and enhances message service logic to handle private chat creation and retrieval. Also registers new services and validators in DI, and updates related tests.

Govor.API/Extensions/ConfigurationProgramExtensions.cs

@@ -17,6 +17,7 @@ using Govor.Core.Repositories.Groups;
 using Govor.Core.Repositories.Invaites;
 using Govor.Core.Repositories.MediasAttachments;
 using Govor.Core.Repositories.Messages;
+using Govor.Core.Repositories.PrivateChats;
 using Govor.Core.Repositories.Users;
 using Govor.Data;
 using Govor.Data.Repositories;
@@ -61,6 +62,7 @@ public static class ConfigurationProgramExtensions
         services.AddScoped<IAdminsRepository, AdminsRepository>();
         services.AddScoped<IMediaAttachmentsRepository, MediaAttachmentsRepository>();
         services.AddScoped<IFriendshipsRepository, FriendshipsRepository>();
+        services.AddScoped<IPrivateChatsRepository, PrivateChatsRepository>();
         services.AddScoped<IGroupsRepository, GroupRepository>();
     }
 
@@ -72,6 +74,7 @@ public static class ConfigurationProgramExtensions
         services.AddScoped<IObjectValidator<Admin>, AdminValidator>();
         services.AddScoped<IObjectValidator<Invitation>, InvitationValidator>();
         services.AddScoped<IObjectValidator<Friendship>, FriendshipValidator>();
+        services.AddScoped<IObjectValidator<PrivateChat>, PrivateChatValidator>();
     }
 
     public static void AddGovorDbContext(this IServiceCollection services, IConfiguration configuration)