Add a project-level "Archive all threads" action in Codex App

I’m using the Codex macOS app. Archiving works well per thread, but for projects with many older threads it is slow to archive them one by one.

Please add a project-level action next to the project name that archives all threads in that project in one step. A confirmation step with the number of affected threads would help avoid mistakes, and keeping unarchive available for recovery would be ideal.