feat: добавил ограничение записи на лекции

backend/UniVerse.Domain/Services/EnrollmentSlotPolicy.cs

@@ -0,0 +1,21 @@
+namespace UniVerse.Domain.Services;
+
+public static class EnrollmentSlotPolicy
+{
+    private static readonly IReadOnlyList<EnrollmentSlotRule> SlotRules =
+    [
+        new(1, 3),
+        new(3, 5),
+        new(4, 7)
+    ];
+
+    public static IReadOnlyList<EnrollmentSlotRule> Rules => SlotRules;
+
+    public static int GetLimitForLevel(int level) =>
+        SlotRules
+            .Where(rule => rule.Level <= level)
+            .OrderBy(rule => rule.Level)
+            .LastOrDefault()?.Slots ?? SlotRules[0].Slots;
+}
+
+public sealed record EnrollmentSlotRule(int Level, int Slots);