Work Plan - Optimize Resize Performance

Request

The user reported that the resize functionality was laggy, slow, and inconsistent.

Refactoring Strategy:
- Removed React state updates from the mousemove event loop.
- Used useRef to track sidebarWidth and poolHeight values.
- Used requestAnimationFrame to throttle DOM updates directly during resizing.
- Only triggered React state updates (re-renders) on mouseup.
DraftView.tsx:
- Implemented resizingState ref.
- Modified handleMouseDown to initiate direct DOM resizing.
- Modified onMouseMove to update element styles directly.
- Modified onMouseUp to sync final size to React state.
- Applied refs to Sidebar and Pool resizing areas.
DeckBuilderView.tsx:
- Implemented identical ref-based + requestAnimationFrame resizing logic.
- Fixed several HTML nesting errors introduced during the complex refactoring process.

Performance: Resizing should now be smooth (60fps) as it avoids React reconciliation during the drag.
Consistency: The handle should no longer "slip" because the visual update is faster.
Persistence: The final size is still saved to state (and thus localStorage) after release.