Add login_with_refresh_token() for token-only authentication

[epheterson]

Currently the only public way to authenticate is login(username, password), so anything that wants to keep a session across restarts has to reach into a private attribute:

api = LucidAPI()
api._refresh_token = stored_token   # private
await api.authentication_refresh()

This adds login_with_refresh_token(token) and a public refresh_token property, so the round trip has a supported path.

Why it matters beyond tidiness. Lucid permits one account per car and the mobile app has no secondary logins, so a stored password is the primary account credential — it unlocks the doors and opens the frunk, and it can't be revoked without a password change. A refresh token can be revoked with "log out all devices." Letting integrations store the weaker secret is a meaningful difference for anything unattended.

One caveat, documented in the docstring: GetNewJWTTokenResponse carries only session_info — no user_profile and no user_vehicle_data — so api.user stays None after a token login until fetch_vehicles() is called. Worth knowing for downstreams that assert on api.user after authenticating.

Tested against a real vehicle (Gravity, 1.4.1 + this patch):

session valid for: 5:59:59
api.user is None (documented): True
public refresh_token property matches input: True
vehicles after fetch_vehicles(): ['TARS']
invalid token raises: APIError

black --check clean.

A behavioural note you may want to document separately: the refresh token does not appear to rotate. Three consecutive authentication_refresh() calls returned a byte-identical token, and replaying an earlier one still worked. That's convenient — several processes can share a stored token without coordination — but it does mean it's a long-lived bearer credential rather than a self-rotating one, and SessionInfo carries no expiry field for it, so its lifetime isn't discoverable from the API. I've described it that way in the property docstring; happy to soften or drop that wording if it doesn't match your understanding.

[nshp]

Looks good to me, thanks!