fix: Cart Functionality: Added Quantity Modification and Item Removal issue:#50

[kaali001]

Description

This pull request adds functionality to the cart items, allowing users to increase or decrease the quantity of items and remove items from the cart. and implemented logic for empty cart.

Changes

• Added handleIncrease, handleDecrease, and handleRemove functions in the Cart component.
• Updated Cartcard component to include +, -, and cross buttons with event handlers for modifying cart items.
• Updated API calls in the Cart component to reflect changes in the cart state on the server.
• Fixed the issue of empty cart logic , improvement in the UI of this component.

How to test

1. Fetch Cart Items:

   • Run the application and navigate to the cart page.
   • Ensure the cart items are fetched and displayed correctly.

2. Increase Item Quantity:

   • Click the + button on any cart item.
   • Verify that the quantity of the item increases by one.
   • Check that the subtotal is updated accordingly.

3. Decrease Item Quantity:

   • Click the - button on any cart item.
   • Verify that the quantity of the item decreases by one (if the quantity is greater than one).
   • Check that the subtotal is updated accordingly.

4. Remove Item from Cart:

   • Click the cross button on any cart item.
   • Verify that the item is removed from the cart.
   • Check that the subtotal is updated accordingly.

5. Check Out:

   • Click the "Check out" button.
   • Ensure the payment process is initiated correctly with the updated total amount
   • Please consider using the closing keyword if the pull request is proposed to

Screenshots

before -

After -

fix an issue already created in the repository
issue: #50

I have fixed four issue of cart page, so if possible please increase the level.

[dvjsharma]

Changes looks good. Tested, working as expected.