chore: organize homework into first-part directory

first-part/hw-01/src/MutableClass.java

@@ -0,0 +1,20 @@
+class MutableClass {
+  MutableClass(int value) {
+    this.setValue(value);
+  }
+
+  // Конструктор копирования
+  public MutableClass(MutableClass other) {
+    this.value = other.value;
+  }
+
+  public int getValue() {
+    return value;
+  }
+
+  public void setValue(int value) {
+    this.value = value;
+  }
+
+  private int value;
+}