feat: implement composite pattern for student search

app/src/main/java/ru/project/search/AverageGradeRangeCriteria.java

@@ -0,0 +1,22 @@
+package ru.project.search;
+
+import ru.project.student.Student;
+
+public class AverageGradeRangeCriteria implements StudentSearchCriteria {
+    private final double min;
+    private final double max;
+
+    public AverageGradeRangeCriteria(double min, double max) {
+        if (min > max) {
+            throw new IllegalArgumentException("Min grade must be <= max grade");
+        }
+        this.min = min;
+        this.max = max;
+    }
+
+    @Override
+    public boolean matches(Student student) {
+        double grade = student.getAverageGrade();
+        return grade >= min && grade <= max;
+    }
+}