Update README with comprehensive documentation of new features

- Document database-first architecture and automatic startup population
- Add Docker setup instructions and mobile-responsive UI features
- Include API endpoint documentation and technical architecture details
- Explain optimized PDGA scraping strategy and user-controlled refresh system
- Add performance, reliability, and Docker configuration sections

🤖 Generated with [Claude Code](https://claude.ai/code)

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

README.md

@@ -1,9 +1,10 @@
 # PDGA Ratings Scraper
 
-A web application that scrapes PDGA player ratings and displays them in a sorted table.
+A comprehensive web application that scrapes PDGA player ratings, calculates rating predictions, and displays them with interactive charts and real-time updates.
 
 ## Setup
 
+### Local Development
 1. Install dependencies:
 ```bash
 npm install
@@ -18,15 +19,79 @@ npm start
 
 4. Open http://localhost:3000 in your browser
 
-## Usage
+### Docker (Recommended)
+1. Build and run with Docker:
+```bash
+docker build -t pdga-ratings .
+docker run -p 3000:3000 --name pdga-ratings-container pdga-ratings
+```
 
-- Edit `pdga-numbers.txt` to add/remove players
-- Click "Refresh Ratings" to scrape current ratings
-- Players are automatically sorted by rating (highest first)
+2. Open http://localhost:3000 in your browser
 
 ## Features
 
-- Web scraping of PDGA player ratings
-- Sortable table display
-- Easy player management via text file
-- Real-time rating updates
+### Core Functionality
+- **Database-first architecture**: SQLite database serves as single source of truth
+- **Automatic startup population**: Reads `pdga-numbers.txt` and populates missing players at startup
+- **User-controlled refresh**: Data only updates when user explicitly clicks refresh icons
+- **Optimized PDGA scraping**: Uses `/details` page as baseline + only scrapes NEW tournaments for predictions
+
+### Rating System
+- **Official PDGA ratings**: Current player ratings from PDGA website
+- **Rating predictions**: Multi-day tournament support with weighted calculations
+- **Rating history charts**: Interactive SVG charts with hover tooltips
+- **Rating changes**: Shows recent rating changes with color-coded indicators
+
+### User Interface
+- **Mobile-responsive design**: Optimized layouts for desktop and mobile
+- **Expandable player rows**: Click to view detailed rating history charts
+- **Individual refresh controls**: Separate refresh icons for ratings, predictions, and charts
+- **Progress tracking**: Real-time progress bars for bulk operations
+- **Error handling**: Comprehensive error messages with retry suggestions
+
+### Performance & Reliability
+- **Respectful scraping**: 2-second delays between PDGA requests
+- **Smart caching**: Database persistence with user-controlled freshness
+- **Docker optimization**: Alpine Linux with Chromium for stable Puppeteer execution
+- **Retry logic**: Automatic retries with fallback strategies for network issues
+
+## Usage
+
+### Basic Operations
+- **View ratings**: Page loads instantly from database
+- **Refresh player data**: Click refresh icon next to player rating
+- **Refresh predictions**: Click refresh icon next to predicted rating
+- **View rating history**: Click on any player row to expand chart
+- **Refresh charts**: Click refresh icon in chart title
+
+### Player Management
+- Edit `pdga-numbers.txt` to add/remove players
+- Restart server to automatically populate new players
+- Use "Load All" button to force refresh all player data
+
+### API Endpoints
+- `GET /api/ratings` - Get all player ratings from database
+- `POST /api/refresh-player/:pdgaNumber` - Refresh specific player
+- `POST /api/refresh-round-history/:pdgaNumber` - Refresh player predictions
+- `GET /api/rating-history/:pdgaNumber` - Get player rating history
+- `GET /api/database-status` - Check database population status
+
+## Technical Details
+
+### Architecture
+- **Backend**: Node.js + Express + SQLite
+- **Frontend**: Vanilla JavaScript with Server-Sent Events
+- **Scraping**: Puppeteer with Alpine Linux + Chromium
+- **Charts**: Custom SVG implementation with interactive tooltips
+
+### PDGA Integration
+- Uses official PDGA `/details` page for rating calculations
+- Only scrapes tournaments played AFTER last official round
+- Respects PDGA servers with proper delays and retry logic
+- Handles both current ratings and historical data
+
+### Docker Configuration
+- Alpine Linux base for minimal footprint
+- Pre-installed Chromium for Puppeteer
+- Non-root user for security
+- Proper volume mounting for data persistence