架构性调整【懒得区分了，哈哈哈哈】，主要是跑通了第一个功能测试

src/main/java/com/guo/learningprogresstracker/controller/StudySessionController.java

@@ -0,0 +1,9 @@
+package com.guo.learningprogresstracker.controller;
+
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class StudySessionController {
+
+
+}