LiquidGlassContainer's native glass rendered short of its frame whenever
that frame reached into the bottom safe area (floating bottom panel on
home-indicator devices). UIHostingController propagates the screen's
safe area into its SwiftUI content, so the hosted GeometryReader/shape
was inset by the overlap.

Fixed by @fbernack in PR #64 via hostingController.safeAreaRegions = [].

Reproduced and verified on a physical iPhone (iOS 26.5): a 140pt panel
flush to the bottom of a 34pt inset rendered ~21pt short before the fix
and filled its frame completely after. Reporter measured up to 22pt on
an iPhone 17 Pro / iOS 26.4 simulator.

macOS unaffected — NSHostingController, and macOS windows have no
bottom safe-area inset in practice.

Adds Testing -> "PR #64: LiquidGlass safe-area clip" demo with live
offset/height/shape controls and Flutter-drawn frame + safe-area
reference markers so the defect is directly visible.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>