seller: redesign store settings dashboard with colorful cards

- Added new dashboard overview with Quick Access colorful cards
- Each setting section has unique color gradient and icon
- Added Store Summary card showing store details and metrics
- Added Trading Stats card with published products, reviews, completion, rating
- Implemented responsive grid layout for all card sections
- Enhanced visual design with gradients, hover effects, and smooth transitions
- Cards are fully clickable and navigate to respective settings pages

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
