feat: Add basic C++ calculator

[Satvik-Singh192]

Description

This pull request introduces a simple, command-line arithmetic calculator implemented in C++.
The design adheres to Object-Oriented Programming (OOP) principles for modularity and maintainability.

Key Features

• Modular Design: Logic is split into Calculator.h (interface) and Calculator.cpp (implementation).
• Core Operations: Supports addition, subtraction, multiplication, and division.
• Error Handling: Implements robust exception handling to catch and report division by zero errors gracefully.

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Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

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Issues

This pull request closes the feature request: #2

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Checklist

• I have read the Contributing Guidelines.