Groove Utilities Task Archive

This handles the cleanup work of archiving completed tasks from your Groove workflow into whatever backend you're using (beans, Linear, or GitHub). It reads your backend config from `.groove/index.md`, shows you what's about to be archived, and makes you confirm before doing anything. The smart bit is that it never runs automatically during daily standup routines, only when you explicitly ask for it, which prevents accidental bulk archiving. It adapts to each backend's quirks: beans archives everything in one go, Linear marks issues as archived, and GitHub closes them. You get a count of what was archived when it's done. Good for keeping your task list clean without the anxiety of automatic cleanup.