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/Migrations/20260512123000_UserNotifications.cs

@@ -0,0 +1,54 @@
+using System;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using UniVerse.Infrastructure.Data;
+
+#nullable disable
+
+namespace UniVerse.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    [DbContext(typeof(AppDbContext))]
+    [Migration("20260512123000_UserNotifications")]
+    public partial class UserNotifications : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "user_notifications",
+                columns: table => new
+                {
+                    id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", Npgsql.EntityFrameworkCore.PostgreSQL.Metadata.NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    user_id = table.Column<int>(type: "integer", nullable: false),
+                    type = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: false),
+                    title = table.Column<string>(type: "character varying(255)", maxLength: 255, nullable: false),
+                    body = table.Column<string>(type: "character varying(1000)", maxLength: 1000, nullable: false),
+                    is_read = table.Column<bool>(type: "boolean", nullable: false, defaultValue: false),
+                    created_at = table.Column<DateTime>(type: "timestamp with time zone", nullable: false, defaultValueSql: "NOW()")
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_user_notifications", x => x.id);
+                    table.ForeignKey(
+                        name: "FK_user_notifications_users_user_id",
+                        column: x => x.user_id,
+                        principalTable: "users",
+                        principalColumn: "id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_user_notifications_user_id_created_at",
+                table: "user_notifications",
+                columns: new[] { "user_id", "created_at" });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(name: "user_notifications");
+        }
+    }
+}

backend/UniVerse.Infrastructure/Migrations/AppDbContextModelSnapshot.cs

@@ -721,6 +721,56 @@ namespace UniVerse.Infrastructure.Migrations
                     b.ToTable("user_achievements", (string)null);
                 });
 
+            modelBuilder.Entity("UniVerse.Domain.Entities.UserNotification", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasColumnName("id");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("Body")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("character varying(1000)")
+                        .HasColumnName("body");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("created_at")
+                        .HasDefaultValueSql("NOW()");
+
+                    b.Property<bool>("IsRead")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("boolean")
+                        .HasDefaultValue(false)
+                        .HasColumnName("is_read");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)")
+                        .HasColumnName("title");
+
+                    b.Property<string>("Type")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)")
+                        .HasColumnName("type");
+
+                    b.Property<int>("UserId")
+                        .HasColumnType("integer")
+                        .HasColumnName("user_id");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId", "CreatedAt");
+
+                    b.ToTable("user_notifications", (string)null);
+                });
+
             modelBuilder.Entity("UniVerse.Domain.Entities.UserRoleAssignment", b =>
                 {
                     b.Property<int>("UserId")
@@ -905,6 +955,17 @@ namespace UniVerse.Infrastructure.Migrations
                     b.Navigation("User");
                 });
 
+            modelBuilder.Entity("UniVerse.Domain.Entities.UserNotification", b =>
+                {
+                    b.HasOne("UniVerse.Domain.Entities.User", "User")
+                        .WithMany("Notifications")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
             modelBuilder.Entity("UniVerse.Domain.Entities.UserRoleAssignment", b =>
                 {
                     b.HasOne("UniVerse.Domain.Entities.User", "User")
@@ -958,6 +1019,8 @@ namespace UniVerse.Infrastructure.Migrations
 
                     b.Navigation("Enrollments");
 
+                    b.Navigation("Notifications");
+
                     b.Navigation("RefreshTokens");
 
                     b.Navigation("Reviews");