0.3.0

        Add secure account linking for social authentication providers.

New features:

• Configurable account_linking settings:
  • enabled: Enable/disable account linking (required for both manual and automatic linking)
  • allow_different_emails: Allow linking accounts with different emails
• Manual account linking via response_type=link_code flow
• Automatic account linking by email during login

Security improvements:

• Fail fast at authorize time if linking is disabled (better UX)
• Email verification checks for untrusted providers
• Link codes are bound to the user who initiated the flow

This release was contributed by @patrick91 in #13