Add all the outstanding pieces for state management of new command menu:
- Pages state (handles routing between command menu views, e.g., docs
search, AI, etc.)
- View state (handles opening and closing and initiation (needed for
lazy loading))
- Query state (handles active search term)
Introduces the first (very small) slice of the new command menu as a `ui-pattern`.
This slice just handles state for available commands. It isn't hooked up to anything yet.
Jordi Enric