feat: add UserAlreadyExistsException for handling user registration conflicts

Author: OtavioXimarelli

src/main/java/com/otavio/aifoodapp/exception/UserAlreadyExistsException.java

@@ -0,0 +1,12 @@
+package com.otavio.aifoodapp.exception;
+
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(HttpStatus.CONFLICT)
+public class UserAlreadyExistsException extends RuntimeException{
+    public UserAlreadyExistsException(String message) {
+        super(message);
+    }
+}