openai/gpt-5.3-chat → A (9:1)

Commit A introduces a full invite system end-to-end: new RPC commands, server-side state and redemption logic, auth flow integration, reducer updates, timeline integration, CLI support, and comprehensive tests. It significantly expands core functionality. Commit B is a focused UI improvement making an existing pin icon clickable to unpin, with minor rendering and CSS changes plus test updates. The scope and impact of A are far greater.