Add user stats page with progress bars

Overview

Add a stats page that gives users a sense of accomplishment without over-gamifying the experience. The goal is to support intrinsic motivation rather than replace it with extrinsic rewards.

Feature Description

Display progress bars for measurable metrics (e.g., total evaluations, sessions completed). Each bar uses a logarithmic scale with tiers:

The tier color changes as users progress, providing visual feedback on their contribution level.

Implementation

Backend

• New API endpoint: GET /api/user/stats returning user metrics
• Track total evaluations submitted, sessions completed, etc.

Frontend

• New page at /app/stats/page.tsx
• Progress bar component with tier-based coloring
• Link in Header for authenticated users
• Use existing UI components and Tailwind styling

Stats to track

• Total evaluations submitted
• Number of sessions completed
• (Optional) Breakdown by property type

Design Notes

• Keep the UI minimal and informative, not flashy
• Avoid language like "achievements" or "rewards"
• Frame as contribution metrics, not game scores

Start by locating the backend entry point for GET /api/user/stats and the frontend page at /app/stats/page.tsx, then review the Header and existing UI components with Tailwind styling. Done means authenticated users can open a minimal stats page showing contribution metrics with logarithmic progress bars and tier-based colors, backed by the new endpoint.