Use forward references after dropping Python < 3.14 support

[suhaibmujahid]

The relationship definition uses 'GeneratedComment' as a string but the class is defined in the same file. While forward references work, it's more consistent to use the actual class since it's already defined above. Change line 129 from 'Feedback' to Feedback and line 165 from 'GeneratedComment' to GeneratedComment (without quotes).

Originally posted by @Copilot in #5684