feat: добавил личные уведомления для пользователей

Реализовал хранение, получение и отметку прочитанными пользовательских уведомлений. Обновил фронтенд для отображения и управления уведомлениями в профиле студента.

backend/UniVerse.Infrastructure/Services/GamificationService.cs

@@ -5,6 +5,7 @@ using System.Globalization;
 using UniVerse.Application.DTOs.Achievements;
 using UniVerse.Application.DTOs.Common;
 using UniVerse.Application.DTOs.Gamification;
+using UniVerse.Application.DTOs.Notifications;
 using UniVerse.Application.Interfaces;
 using UniVerse.Application.Mappings;
 using UniVerse.Domain.Entities;
@@ -17,11 +18,16 @@ public class GamificationService : IGamificationService
 {
     private readonly AppDbContext _db;
     private readonly IConfiguration _config;
+    private readonly INotificationService _notifications;
     private readonly ILogger<GamificationService> _logger;
 
-    public GamificationService(AppDbContext db, IConfiguration config, ILogger<GamificationService> logger)
+    public GamificationService(
+        AppDbContext db,
+        IConfiguration config,
+        INotificationService notifications,
+        ILogger<GamificationService> logger)
     {
-        _db = db; _config = config; _logger = logger;
+        _db = db; _config = config; _notifications = notifications; _logger = logger;
     }
 
     public async Task AwardCoinsAsync(int userId, int amount, CoinTransactionType type,
@@ -91,10 +97,43 @@ public class GamificationService : IGamificationService
                     achievementId: achievement.Id, description: $"Achievement: {achievement.Name}");
                 earnedCoins += achievement.CoinReward;
             }
+
+            await TryNotifyAchievementAsync(user, achievement);
         }
         await _db.SaveChangesAsync();
     }
 
+    private async Task TryNotifyAchievementAsync(User user, Achievement achievement)
+    {
+        try
+        {
+            var title = $"Новое достижение: {achievement.Name}";
+            var rewardText = achievement.CoinReward > 0
+                ? $" Награда: {achievement.CoinReward} монет."
+                : string.Empty;
+            var body = $"{achievement.Description ?? "Вы выполнили условие достижения."}{rewardText}";
+
+            await _notifications.CreateUserNotificationAsync(user.Id, "achievement", title, body);
+
+            await _notifications.SendAsync(new NotificationMessage(
+                NotificationChannels.Email,
+                user.Email,
+                title,
+                $"Здравствуйте, {user.DisplayName ?? user.Email}!\n\nПоздравляем: вы получили достижение «{achievement.Name}» в UniVerse.\n\n{body}",
+                user.DisplayName,
+                new Dictionary<string, string>
+                {
+                    ["event"] = "achievement_earned",
+                    ["achievement_id"] = achievement.Id.ToString(),
+                    ["achievement_name"] = achievement.Name
+                }));
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "Failed to send achievement notification {AchievementId} to user {UserId}", achievement.Id, user.Id);
+        }
+    }
+
     private static bool TryParseCondition(string? condition, out string type, out int value)
     {
         type = string.Empty;