Foundation for the premium UI overhaul:
- P3 DisplayP3 color pipeline (all tokens in wide gamut)
- SquircleShape (iOS-style superellipse with G2 continuity)
- KaizenShapes token system (xs/sm/md/lg/xl/pill/circle)
- Multi-layer ShadowStack system (level 0–4)
- GlassSurface composable with RenderEffect blur + API fallback
- Motion tokens (easing curves, spring specs, durations)
- Tilt sensor state (GAME_ROTATION_VECTOR, lifecycle-aware)
- 4-theme system (Amber/Blau/Mono/Aurora) with AccentScheme
- ThemeRegistry + CompositionLocal for accent propagation
- Unit tests for colors, shapes, shadows, themes
