ShaderEffect refactor: construct from a shader path with an indexer uniform bag.

Uniforms accept per-frame functions and a built-in clock:

Hud.Overlay() - full-screen HUD root column layout, pointer-through (does not swallow game input)

Hud.Fill() - absolute layer, pointer-through; the standard Hud for shader effects

Hud.Scrim(color) - edge-pinned tinted backdrop for modals. PointerEvents left to the caller so it can toggle on open/close

Hud.Wallpaper(texture, path) - background image layer by texture or by path

Hud.Anchored(anchor, content, padding) - pins content to a screen corner or edge center, pointer-through

Hud.Spacer() - flex-grow gap that pushes siblings apart

Hud.Divider(color) - 1px full-width horizontal rule. low-alpha white by default.

Controls.Button(...) ready-made button and Children.AddIf(condition, child)

Container.Disabled forces pointer-off and dims, per node, applied after state variants.

Container.SwallowClick stops a click from bubbling

PointerDrag frame-polled move/resize helper, UI-scale correct via Current(panel)

PaddingX/Y

MarginX/Y

BorderTopRadius

BorderBottomRadius

BorderLeftRadius

BorderRightRadius

All 9 animation dampers gain Tick(dt).

KeyTracker.Pressed(name) rising-edge query.

Text.Style takes a TextStyle bundle for one-shot font blocks.

Cell.Mount<TCell>(key, seed, configure): seed runs once at first mount, configure every rebuild.

Image gains a positioning subset and defaults BackgroundRepeat to NoRepeat, stopping ObjectFit.Contain tiling