feat: add Chargeable and Refuelable interfaces

src/main/java/org/example/behavior/Chargeable.java

@@ -0,0 +1,5 @@
+package org.example.behavior;
+
+public interface Chargeable {
+    void charge(double amount);
+}

src/main/java/org/example/behavior/Refuelable.java

@@ -0,0 +1,5 @@
+package org.example.behavior;
+
+public interface Refuelable {
+    void refuel(double amount);
+}