Fix Hotbar Setup navigation past Export leaving the active view unchanged

[Hmbown]

Observed behavior

In Hotbar Setup, navigate down through the menu until the lowest visible item, Export, is selected. Pressing Down again advances the menu/navigation state, but the active content view does not change. This leaves keyboard focus and the rendered setup pane out of sync.

Reproduction

1. Open Hotbar Setup.
2. Press Down until Export is selected.
3. Press Down once more.
4. Observe that navigation continues but the visible setup view remains unchanged.

Expected behavior

At the end of the menu, navigation must have one deliberate, visible result: stay on Export, wrap to a documented destination, or move to the next pane. It must never leave an invisible/new selection while rendering the previous view.

Acceptance criteria

• Use one source of truth for the focused menu item and the rendered Hotbar Setup pane.
• Define and implement the Down-key boundary behavior after Export.
• Keep highlight, focus/accessibility state, and visible content synchronized for every Hotbar Setup item.
• Add a regression test that drives Down through Export and asserts both selected item and active view.
• Verify the same boundary behavior with mouse/scroll navigation if those inputs can change the Hotbar Setup selection.