Use @FocusState with programmatic assignment on appear instead of
prefersDefaultFocus, which is broken when the target sits inside a
ScrollView/LazyVGrid on tvOS. A 0.15s delay gives the grid time to
materialize cells before the focus write.
Replace the toolbar-based controls with an inline header row on tvOS so
the View Options and clear buttons are reachable with the remote. Drop
the navigation title, add an inline title, and disable ScrollView
clipping so the focus scale effect isn't clipped.
On tvOS, ContentUnavailableView inside a Group doesn't expand to fill
available space — it sizes to content and aligns top-leading. Add
.frame(maxWidth: .infinity, maxHeight: .infinity) to all instances
so they center correctly in their parent containers.
