Simplify and Focus Invite Members Callout CodePublic

The user aimed to simplify and tighten the invite members callout code by extracting duplicated HTTP request logic into a small shared helper, then later removing it to reduce complexity. They also moved member fetching into the callout component and removed the sidebar members list for a cleaner, more focused implementation. The final outcome is a minimal, well-commented, and easier-to-maintain codebase with clear separation of concerns and no unnecessary generalization.