Increase oauth state cookie lifetime

[dokterbob]

Is your feature request related to a problem? Please describe.
During OAuth logins, Chainlit sets a state cookie in the browser, which is used to prevent attackers from logging in on behalf of other users by stealing the URL users are being redirected to after OAuth provider login.

The lifetime of this cookie is currently hardcoded to 3 minutes.

When using email to login, this is often not enough, severely degrading user experience.

Describe the solution you'd like
Make the state lifetime cookie configurable.

Describe alternatives you've considered

1. Setting it to default session lifetime: unnecessarily decreases security.
2. Increase the default: same.

Additional context
Users experiencing this will see a rather unfriendly 'Unauthorized' JSON, the UX of which deserves a separate issue.

Possibly related:

• Use encrypted state token instead of cookie for oauth #1127
• Serving custom error pages #1537