Fetching Github username (not Display Name)

[wangeguo]

Need to research how to correctly retrieve the user's Github username (unique login identifier) in Better Auth, instead of their public Display Name. Potential solutions may involve before or after Hooks. Key questions:

1. Difference between username and display name in Github API response
2. Whether Better Auth defaults to fetching the wrong field, requiring override/extend
3. Hook best practices (timing, data modification approach)