Centralize workspace navigation behind a small route-derived API so the workspace shell reads active selection from the current Expo Router route instead of a separately synchronized store.
Remove the stale layout-driven active-workspace write that regressed web after 02e5b564.
Replace 8-mock hook test (expo-router, layout, platform, navigation,
4 stores) with a pure unit test of the routing decision. The hook now
reads pathname/layout/key, calls routeKeyboardShortcut, and dispatches
the resulting ShortcutAction — no behaviour change.