[Story] shadcn/ui Component System Setup

## User Story Description
As a developer
I want to have shadcn/ui components available
So I can build consistent UI elements efficiently

## Acceptance Criteria
- [ ] Initialize shadcn/ui
- [ ] Configure design tokens
- [ ] Set up component architecture
- [ ] Add button component
- [ ] Configure theme variables

## Technical Notes
N/A

## Related Epic
Related to Epic #69 