Support Legacy (Alumni) Users in User Schema

[YeIIcw]

Description
We are the University of Toronto Machine Intelligence Team, and our website includes a project page showcasing all the projects our members (past and present) have worked on. Many alumni no longer have active accounts in our current system, but they contributed significantly to past projects and should still be featured on our site.

• We mark alumni as legacy: true in our user schema.
• If we later want to associate an alumnus with an existing user account, we manually set legacyClaimed: true.
• This approach ensures we properly recognize alumni for their past work, while allowing us to link them to current users when needed.

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User Story
As an admin of the University of Toronto Machine Intelligence Team website:

1. I need the ability to create or import alumni user entries as “legacy” so their past work is recognized.
2. I want the option to link an existing GitHub-auth’d (or otherwise authenticated) user to a legacy user.
3. When linked, the system should mark the legacy user as claimed and handle any merges or updates to the user’s information.

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Acceptance Criteria

1. Database / Schema Updates

   • Add legacy (boolean) and legacyClaimed (boolean) fields.
   • Ensure existing non-alumni users remain with legacy: false and legacyClaimed: false by default.

2. Linking Functionality

   • Admins can link a legacy user to an existing GitHub-auth’d user.
   • Linking sets legacyClaimed = true.
   • (Optionally) merge relevant fields (e.g., name, email, bio).