fix(oauth2): log in with the app's HTTPS callback, Porsche rejects the custom scheme - #101

Logins fail since around 10 November (reported in CJNE/ha-porscheconnect#465 and CJNE/ha-porscheconnect#466): the Porsche identity server answers /authorize with 403 unauthorized_client: Callback URL mismatch for my-porsche-app://auth0/callback, before the e-mail is sent. Installations keep working until their refresh token is rejected, then the full login fails and Reconfigure reports invalid authentication.

Change

• REDIRECT_URI is now the HTTPS app link the current My Porsche app uses with the same client_id: https://security.porsche.com/auth/en-GB/app/callback. The custom schemes my-porsche-app:// and my-porsche-app-auth0:// are both refused, and only en-GB is registered for the HTTPS link.
• When /authorize does not answer 302, the error message now carries the HTTP status (Could not fetch authorization code: HTTP 403) instead of hiding it.

The resume flow already reads the code from the redirect Location without following it, so nothing else changes.

Tests

• On this branch, /authorize with the old URI gives Could not fetch authorization code: HTTP 403, and with the new one a 302 to the login screen.
• The full login with this redirect URI (captcha, resume, token exchange, vehicle list and overview) has been running in my fork since 12 November, with users on a 718 Cayman GT4 RS, a Cayenne E-Hybrid and a Taycan 4S.
• ruff check passes.

EDIT: schaepi85 reached the same fix independently in CJNE/ha-porscheconnect#466. The User-Agent bump is not needed for the login and is left out. Once this is released, ha-porscheconnect needs the new version pinned in its manifest.