重构项目结构，移除Assignment相关功能，优化Submission模块

TechHelper.Server/Repository/KeyPointRepository.cs

@@ -0,0 +1,13 @@
+using Entities.Contracts;
+using SharedDATA.Api;
+using TechHelper.Context;
+
+namespace TechHelper.Repository
+{
+    public class KeyPointRepository : Repository<KeyPoint>, IRepository<KeyPoint>
+    {
+        public KeyPointRepository(ApplicationContext context) : base(context)
+        {
+        }
+    }
+}