Feature/calculator

[Adi-Sin101]

This pull request introduces two new classes to the codebase: a simple Calculator utility and a comprehensive Student model. The Calculator provides basic arithmetic operations, while the Student class encapsulates student data and related behaviors with constructors, accessors, mutators, and utility methods.

New Features:

• Added Calculator class with methods for addition, subtraction, multiplication, and division (with division-by-zero protection). (src/Features/Calculator.java)

• Added Student class with:

  • Fields for id, name, email, department, and gpa
  • Multiple constructors (no-arg, parameterized, and copy)
  • Getter and setter methods (with GPA validation)
  • Builder-style "with" methods for fluent object creation
  • Overridden toString, equals, and hashCode methods for proper object representation and comparison (src/Features/Student.java)