GitLab, Authentik, Zitadel, Clerk and Azure identities were keyed by the
provider name only, so a user with the same subject on another instance
could sign in as the linked user after the base URL or tenant changed.
The issuer column now stores the normalized instance, existing rows are
backfilled from the current settings, and oauth:rekey handles host renames.
Before OAuth identities existed, OAuth sign-in matched users by email
only. Add a created_before_oauth_identities flag, set for every user at
upgrade time, so their first OAuth identity links without a provider
email verification claim. The flag is cleared once an identity links.
Also trust Microsoft Entra ID user principal names and GitLab confirmed
primary emails as verified, and pass the email to hasVerifiedEmail.
Add tests using real provider payloads.
Add OIDC discovery, JWKS validation, Socialite integration, OAuth identity linking, and configurable registration policy for password and SSO signups. Update related settings/profile UI and tests.