fix: финальные правки ревью для issue #39

- PublicSession.razor: добавлена обработка ?register=1, AuthStateProvider,
  TryGetPlatformIdentity, кнопки записи для авторизованных/неавторизованных
  пользователей, отображение результата регистрации
- CreateSessionHandler: добавлен cover_image_url в INSERT SQL
- DiscordProjectStructureTests: версия 3.4.0 во всех проверках
- README.md: актуальная версия v3.4.0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/GmRelay.Shared/Features/Sessions/CreateSession/CreateSessionHandler.cs

@@ -118,8 +118,8 @@ public sealed class CreateSessionHandler(
             {
                 var sessionId = await connection.ExecuteScalarAsync<Guid>(
                     """
-                    INSERT INTO sessions (batch_id, group_id, title, join_link, scheduled_at, status, max_players, system, description, format, duration_minutes, is_one_shot)
-                    VALUES (@BatchId, @GroupId, @Title, @Link, @ScheduledAt, @Status, @MaxPlayers, @System, @Description, @Format, @DurationMinutes, @IsOneShot)
+                    INSERT INTO sessions (batch_id, group_id, title, join_link, scheduled_at, status, max_players, system, description, format, duration_minutes, is_one_shot, cover_image_url)
+                    VALUES (@BatchId, @GroupId, @Title, @Link, @ScheduledAt, @Status, @MaxPlayers, @System, @Description, @Format, @DurationMinutes, @IsOneShot, @CoverImageUrl)
                     RETURNING id;
                     """,
                     new
@@ -135,7 +135,8 @@ public sealed class CreateSessionHandler(
                         command.Description,
                         command.Format,
                         DurationMinutes = command.DurationMinutes,
-                        IsOneShot = command.IsOneShot
+                        IsOneShot = command.IsOneShot,
+                        CoverImageUrl = command.ImageReference
                     },
                     transaction);