Refactor: move route handling to separate package and function

[biisal]

This pull request refactors the way HTTP routes are registered and handled in the application by introducing a centralized routing module. The main logic for route registration is moved from main.go into a new routes package, improving maintainability and scalability for future route additions.

Routing Refactor:

• Introduced a new internal/api/routes/routes.go file that encapsulates route registration logic, including a helper function for building route strings and a dedicated function for registering contact-related routes.
• Replaced direct route handling in cmd/camp/main.go with a call to the new routes.Register function, passing the database connection and using the returned handler in the HTTP server.
• Updated imports in cmd/camp/main.go to use the new routes package instead of the previous contact package for route registration.