Module input/input-handler/dimension-navigation/setup

Dimension-navigation lifecycle bodies extracted from input-handler.ts.

Three functions live here:

• clearDimensionUI(ctx) — dispose sliders + animation manager + listener
• initDimensionSliders(ctx) — wire scene-dims manager → optional slider panel → animation manager → reactive listener
• initAnimationManager(ctx) — construct DimensionAnimationManager

The orchestrator owns the mutable state (animationManager, dimensionSliders, sceneDimsListener, selectedDimension) and exposes it through getter/setter callbacks on DimNavSetupCtx. The ctx never carries this; setup functions read live state at call time.