Fixed issue with first user not being made admin

[hanzlamateen]

Summary

🤖 Generated by Copilot at b137218

Improved documentation and development mode support for identity providers in server-core. Added a comment to explain the guest-only logic and changed the admin type assignment to work with any identity provider type.

References

closes #insert number here

Explanation

🤖 Generated by Copilot at b137218

• Prevent unauthorized account creation with non-password/magiclink identity providers by requiring guest type for those requests (link)
• Allow developers to create admin accounts with any identity provider type in development mode by checking both mode and type conditions (link)

🤖 Generated by Copilot at b137218

guest-only rule
clarified for identities
admin type varies

QA Steps

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Checklist

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• ensure all checks pass
• Changes have been manually QA'd
• Changes reviewed by at least 2 approved reviewers