Enhancement: Refactor calculator from functional to object-oriented design

[Shiza-Yahya]

The calculator is currently written in a functional style. Refactoring it into an object-oriented design would make the code more structured, scalable, and easier to maintain.

Proposed Changes:

Create a Calculator class with methods like add, subtract, multiply, etc.

Store state (current value) inside the class instead of passing numbers around.

This design will make future extensions (e.g., scientific functions, GUI) easier.

Benefits:

Cleaner organization

Easier maintenance

Better scalability

[Haffi-Ansari]

Hey can I work on this issue?
could you please assign it to me?

[Shiza-Yahya]

I don’t have permissions to assign, the repository owner/maintainer can do that.

[Haffi-Ansari]

I have the code ready to commit, so @sohailburki01 (owner) can you assign/give me permission for this issue

[ujala100]

I have to work with this issue.Can you assign it