Before writing the implementation, define the API contract.

We will create the following endpoints:

Method	Endpoint	Purpose
POST	/api/v1/users	Create a user
GET	/api/v1/users	Retrieve users
GET	/api/v1/users/:id	Retrieve a specific user
PUT	/api/v1/users/:id	Replace user information
PATCH	/api/v1/users/:id	Partially update a user
DELETE	/api/v1/users/:id	Delete a user

Each endpoint will return a consistent JSON response.

We will implement the service layer first, followed by controllers and routes.