feat: добавил поддержку подписки на календарь и экспорт расписания лекций в формате .ics

backend/UniVerse.Application/DTOs/Users/UserDtos.cs

@@ -51,6 +51,8 @@ public record AdminDashboardStatsDto(
 
 public record EnrollmentSlotRuleDto(int Level, int Slots);
 
+public record CalendarSubscriptionDto(string FeedUrl);
+
 public record UpdateUserRequest(
     string? DisplayName,
     string? AvatarUrl

backend/UniVerse.Application/Interfaces/IUserService.cs

@@ -12,6 +12,10 @@ public interface IUserService
     Task<UserStatsDto> GetStatsAsync(int id);
     Task<AdminDashboardStatsDto> GetAdminDashboardStatsAsync();
     Task<PagedResult<LectureDto>> GetEnrollmentsAsync(int id, PaginationRequest pagination);
+    Task<string> GetMyEnrollmentsIcsAsync(int userId);
+    Task<string> GetEnrollmentIcsAsync(int userId, int lectureId);
+    Task<string> GetCalendarSubscriptionTokenAsync(int userId);
+    Task<string> GetEnrollmentsIcsBySubscriptionTokenAsync(string token);
     Task<PagedResult<UserDto>> GetAllAsync(UserFilterRequest filter);
     Task SetRolesAsync(int id, IReadOnlyCollection<UserRole> roles);
     Task SetActiveAsync(int id, bool isActive);