Groove Utilities Task Config

This handles the configuration side of a task management integration system that can connect to Beans, Linear, GitHub, or run standalone. It reads and writes a single frontmatter key in `.groove/index.md`, shows you the current backend when called without arguments, and swaps it out when you provide a new one. The nice touch is that it validates your input against the four allowed values and won't let you fat-finger something invalid. If you're building a workflow that needs to switch between different task backends without manually editing config files, this gives you an interactive way to do it. Just know you'll need to run the separate install skill afterward to actually wire up the new backend.