Backend should has a route for handling redirect_uri

[sedovalx]

Backend should has the base route for handling callback errors. Important point: the registered callback address should be the base address for auth code callback and for the token callback.

• [ ] GET /callback?code= - redirect to the frontend (payload: code & referrer?)
• [ ] GET /callback?error= - redirect to the frontend (payload: error & referrer?)
• [ ] GET /callback?access_token= - should complete the frondend "exchangeAuthCode" request #7 with token
• [ ] POST /callback + { access_token } - should complete the frondend "exchangeAuthCode" request #7 with error
• [ ] POST /callback + { error } - should complete the frondend "exchangeAuthCode" request #7 with error

[sedovalx]

non actual - no need in additional error endpoint