Work Plan - Optimize Card Slider Performance

Request

The user reported that resize handlers (likely sliders) were still laggy.

DraftView.tsx:
- Introduced localCardScale for immediate slider feedback.
- Used CSS Variable --card-scale on container to update card sizes entirely via CSS during drag.
- Deferred cardScale state update (which triggers React re-renders) to onMouseUp.
DeckBuilderView.tsx:
- Introduced localCardWidth for immediate slider feedback.
- Used CSS Variable --card-width on container.
- Updated gridTemplateColumns to use var(--card-width).
- Deferred cardWidth state update to onMouseUp.
- Cleaned up duplicate state declarations causing lint errors.
CubeManager.tsx:
- Introduced localCardWidth and CSS Variable --card-width.
- Updated Grid layout to use CSS Variable.
- Deferred state update to onMouseUp.

Performance: Slider dragging should now be 60fps smooth as it touches 0 React components during the drag, only updating a single CSS variable on the root container.
Persistence: Releasing the slider saves the value to state and localStorage.
Logic: complex logic like useArtCrop (which depends on specific widths) updates safely on release, preventing flicker or heavy recalculations during drag.