Update module name and all imports from habit-tracker-api to apocapoc-api.
This reflects the project's new branding as part of the apocapoc ecosystem
(apocapoc-api, apocapoc-web, apocapoc-android).
- Create register and login use cases
- Implement JWT service for token generation and validation
- Add authentication middleware to protect habit endpoints
- Create auth HTTP handlers (register, login)
- Update habit handlers to extract userID from JWT token
- Register/login endpoints: POST /auth/register, POST /auth/login
- Habit endpoints now require Bearer token in Authorization header
- Tested: register -> create habit -> list habits works correctly