Redesign developer overlay as a Liquid Glass HUD

[kyleve]

Reworks the DEBUG-only developer overlay into a HUD-style Liquid Glass surface, and makes the floating window movable, resizable, and aware of the app content behind it. All changes are #if DEBUG and compiled out of release.

What changed

• Hover button — a circular adaptive .glassEffect disc with a .primary glyph (reads in light and dark) instead of the flat stroked ring.
• Chrome — one glass panel surface with a slim HUD control strip (close / drag grabber / full-screen). The tools list clears its scroll background so the glass shows through.
• Full screen — now an inset (~12px) rounded modal over a dimmed, touch-blocking scrim, preserving the .isModal / .screenChanged accessibility behavior.
• Floating window — draggable by its grabber and resizable from a bottom-trailing grip (top-leading corner pinned), clamped on-screen with a minimum size. Center + size (and resting corner) persist across launches via an injected KeyValueStore, kept local to this DEBUG surface rather than routed through the shipping WherePreferences. In-flight translation lives in the view so the store is written once per gesture (not per frame). The persisted layout is re-clamped to the current container on open, so a window saved in one orientation / size class / device can't reopen off-screen or oversized.
• Safe area — the window publishes the footprint it occupies (DeveloperOverlayInsetKey), which RootView applies as safeAreaPadding to the app content only, so screens behind the non-modal HUD scroll clear of it; the HUD's own list reserves room for the resize grip. The footprint math is a pure, unit-tested DeveloperOverlayModel.contentInsets(...): an edge docks only when its near edge is within tolerance and the opposite edge is free (so a window spanning an axis — e.g. the near full-width default — claims nothing), and each inset is capped at 80% of the container so a large window can't collapse the content behind it.
• Strings — adds developer.dragHandle / developer.resizeHandle accessibility labels.

Notable decisions / trade-offs

• Adaptive glass (follows light/dark) rather than an always-dark HUD, to stay consistent with the rest of the app; a dark clamp or a toggle can come later.
• One glass surface for the whole panel (rather than glass-on-glass toolbar + background) to avoid double-rendered material.
• The app-content safeAreaPadding is scoped to the LifecycleContainer only (never the sibling overlay/toast layers) so the overlay's geometry can't feed back on itself. A bottom-docked HUD lifts the tab bar clear of it — intended.
• Drag/resize gestures are measured in the global coordinate space; since each gesture rides the moving/growing window, a .local translation oscillated and read as the window resetting to its prior size/position.
• The window contents use .dynamicTypeSize(.small) to reclaim space in the small HUD.

Testing

• Extended DeveloperOverlayModelTests: default/clamp/move/resize geometry, persistence round-trip via InMemoryKeyValueStore, layout survival across a full-screen toggle, the content-inset footprint (each docking direction, corner, axis-spanning, the cap, the empty-container guard), and the clamp-on-restore path.
• WhereUITests passes locally (tuist test WhereUITests, iPhone 17 / iOS 26.2) and swiftformat --lint is clean.