Experienced React Frontend Developer for Sales Analytics Dashboard with Advanced Features

We are seeking a skilled React frontend developer to build a comprehensive sales analytics dashboard. This project involves creating a user-friendly interface that displays key sales metrics and interactive data visualizations.

Key features of the dashboard will include:
- Display of core metrics: total revenue, number of orders, average order value, and refund rate.
- Interactive charts for: revenue over time, revenue breakdown by category, revenue by channel, and a comparison of new versus returning customers.
- Filtering capabilities: users must be able to filter data by date range, sales channel, and geographical region.
- An orders table: this table will feature search functionality, sorting options, and pagination for efficient data navigation.

The dashboard will connect to a simple rest api for data retrieval. A mock API should also be implemented to allow for independent frontend development without requiring a live backend connection.

Technical requirements:
- Proficiency in React is essential.
- Experience with data fetching libraries such as TanStack Query (React Query) is required.
- Familiarity with a charting library like Recharts or similar is expected.

Design and user experience considerations:
- The dashboard must be fully responsive, ensuring optimal performance and appearance across desktop, tablet, and mobile devices.
- Support for both light and dark themes is required.
- The application should gracefully handle various states, including loading, error, and empty data scenarios.

Bonus skills:
- Experience with testing frameworks such as Vitest or Jest is a plus.

This is a remote, fixed-price freelance project. Interested candidates should submit examples of previous dashboards or React applications they have built, along with their estimated price for the project and a proposed timeline for completion.