feat: 问题数据迁移到数据库；学员详情页URL导航改造；侧边栏统一

- 问题从文件系统迁移到数据库 problems 表
- 移除 PROBLEMS_DIR 配置和文件读取逻辑
- student.html 完整重写：编辑/添加/删除问题，生成方案进度显示
- 学员详情页支持独立URL访问 (/student/<id>)
- 统一侧边栏到 base.html
- 更新文档：DEPLOYMENT_SOP, MODELS, STRUCTURE, FRONTEND_ARCH
- 部署到生产环境 v1.2.0

app/routes/problems.py

@@ -33,7 +33,7 @@ def add_student_problem(student_id):
 
     # 添加或更新问题
     for p in problems:
-        problem_id = p.get("problem_id")
+        problem_id = p.get("problem_id")  # 这是 problems.id
         submitted_ids.add(problem_id)
 
         # 检查是否已存在
@@ -50,7 +50,6 @@ def add_student_problem(student_id):
             problem = StudentProblem(
                 student_id=student_id,
                 problem_id=problem_id,
-                problem_name=p.get("problem_name"),
                 severity=p.get("severity"),
                 level=p.get("level"),
             )
@@ -70,13 +69,38 @@ def clear_student_problems(student_id):
 
 
 @main_bp.route(
-    "/api/students/<int:student_id>/problems/<problem_id>", methods=["DELETE"]
+    "/api/students/<int:student_id>/problems/<int:student_problem_id>", methods=["DELETE"]
 )
 @login_required_json
-def delete_single_problem(student_id, problem_id):
+def delete_single_problem(student_id, student_problem_id):
     """删除学员的单个问题"""
     StudentProblem.query.filter_by(
-        student_id=student_id, problem_id=problem_id
+        id=student_problem_id
     ).delete()
     db.session.commit()
     return jsonify({"message": "删除成功"})
+
+
+@main_bp.route(
+    "/api/students/<int:student_id>/problems/<int:student_problem_id>", methods=["PUT"]
+)
+@login_required_json
+def update_single_problem(student_id, student_problem_id):
+    """更新学员的单个问题（严重程度和级别）"""
+    student = Student.query.get_or_404(student_id)
+    data = request.get_json()
+
+    problem = StudentProblem.query.filter_by(
+        id=student_problem_id
+    ).first()
+
+    if not problem:
+        return jsonify({"error": "问题记录不存在"}), 404
+
+    if "severity" in data:
+        problem.severity = data["severity"]
+    if "level" in data:
+        problem.level = data["level"]
+
+    db.session.commit()
+    return jsonify({"message": "更新成功", "problem": problem.to_dict()})