iOS 26's NavigationStack reserves space for its floating Liquid Glass nav bar
even with `.toolbar(.hidden, for: .navigationBar)` — that's why "Screens"
landed ~180pt down from the dynamic island with a wedge of black above it.
Removed the NavigationStack from the list entirely. Layout is now a plain
top-anchored VStack: top chrome (gear + Screens + plus + search) flush with
the safe-area top, then a ScrollView with LazyVStack of cards filling the
rest of the screen. Sessions present via fullScreenCover instead of
NavigationLink, so we don't need NavigationStack here at all.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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