feat(review): 新增复习内容滚动展示与交互 API

- 新增 /review/feed 端点，合并报告和残片数据按时间倒序返回
- 新增 /review/report/{id} 和 /review/fragment/{id} 端点
- 支持复习内容在首页滚动展示及点击查看详情

src/main/resources/mapper/ReviewMapper.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE mapper
+        PUBLIC "-//mybatis-org//DTD Mapper 3.0//EN"
+        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
+<mapper namespace="com.guo.learningprogresstracker.mapper.ReviewMapper">
+
+    <select id="selectReviewFeed" resultType="com.guo.learningprogresstracker.dto.ReviewFeedItem">
+        SELECT
+            combined.id,
+            combined.session_num   AS sessionNum,
+            combined.source_type   AS sourceType,
+            combined.content,
+            combined.created_time  AS createdTime,
+            t.task_num             AS taskNum,
+            t.task_name            AS taskName
+        FROM (
+            SELECT r.id, r.session_num, r.content, r.created_time, 'REPORT' AS source_type
+            FROM study_reports r
+            WHERE r.deleted = 0
+            UNION ALL
+            SELECT f.id, f.session_num, f.content, f.created_time, 'FRAGMENT' AS source_type
+            FROM study_report_fragments f
+            WHERE f.deleted = 0
+        ) combined
+        JOIN study_sessions ss ON combined.session_num = ss.session_num AND ss.deleted = 0
+        JOIN tasks t ON ss.task_num = t.task_num AND t.deleted = 0
+        ORDER BY combined.created_time DESC
+        LIMIT #{limit}
+    </select>
+
+</mapper>