[BUG] Can't create prejoin via admin interface

[tkiehn]

🐛 Bug Description

Trying to add a prejoin via the admin interface results in an error: Prejoin must have at least one join condition (source and target columns)

📋 Steps to Reproduce

1. Go to http://127.0.0.1:8000/admin/engine/prejoindefinition/add/
2. Add new prejoin
3. Try to save

✅ Expected Behavior

New Prejoin is saved

❌ Actual Behavior

An error occurs: Prejoin must have at least one join condition (source and target columns).

🖼️ Screenshots

🔧 Environment

• TurboVault Engine Version: 0.14.0
• Installation Method: pip install turbovault-engine -U

[tkiehn]

Is there anything else aside from the config in the screenshot that must be done in preparation for the prejoin to be added?