feat:fs: register and login persists auth

refactor:be: renamed constants folder from constant

feat:be: verify token MW created & works; feat:fs: created test-auth route and page

feat:fe: login page created, connected and works

feat:fe: register page connected and works; fix:be: createUser query fixed

feat:fe: added register page, not connected

feat:fe: authSlice created and connected

feat:be:login working

feat:be: checks for already created user before creating

feat:be: can register user

feat:be: /auth/register route-set created

feat:be: /products gives data from db

feat:be: sql scripts added and used

feat:be: GET /products works with mock data

feat:be: node express initialised, /test route connected