Add Swagger Documentation for ShopCart Item

[iLtc]

As a developer
I need the API documented in Swagger
So that I can easily understand how to use the API

Assumptions:

• Need to add Swagger configuration to routes.py
• Need to annotate the code to support Swagger documentation generation
• The documentation endpoint should be on the /apidocs URL

Acceptance Criteria:

When I follow the `/apidocs` URL
Then I can access the documentation JSON in Swagger format