Add Multiplication Feature

[ay-bh]

Is your feature request related to a problem? Please describe.
The current open-source calculator lacks a multiplication function, which limits its usefulness for basic arithmetic operations. Users cannot perform multiplication calculations without leaving the application, causing inconvenience and reducing the calculator's functionality.

Describe the solution you'd like
Add a multiplication feature to the calculator. This should include:

1. A new "Multiply" button alongside the existing Add, Subtract, and Divide buttons
2. Functionality to multiply the two input numbers when the Multiply button is clicked
3. Display the multiplication result in the "Result" field
4. Ensure the multiplication function handles decimal numbers accurately
5. Update the UI to accommodate the new button without cluttering the interface

Describe alternatives you've considered

1. Implementing a more advanced scientific calculator with multiple operations, but this might overcomplicate the simple design
2. Adding a toggle for advanced operations, but this could make the UI less intuitive
3. Using a single "Calculate" button with a dropdown for operation selection, but this would require more clicks from the user

Additional context
The multiplication feature should follow the same design patterns and coding standards as the existing operations. It should also be thoroughly tested to ensure accuracy, especially with edge cases like multiplying by zero or handling very large numbers.