Add Docker support and fix rating change extraction

- Add Dockerfile with optimized Puppeteer configuration for containers
- Add .dockerignore for efficient builds
- Fix rating change regex to match actual PDGA format (no brackets)
- Update Puppeteer launch args for Docker compatibility
- Use new headless mode to resolve deprecation warning

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

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

Dockerfile

@@ -0,0 +1,42 @@
+# Use official Node.js runtime as base image
+FROM node:18-alpine
+
+# Install Chromium and dependencies for Puppeteer
+RUN apk add --no-cache \
+    chromium \
+    nss \
+    freetype \
+    freetype-dev \
+    harfbuzz \
+    ca-certificates \
+    ttf-freefont
+
+# Tell Puppeteer to skip installing Chromium. We'll be using the installed package.
+ENV PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=true \
+    PUPPETEER_EXECUTABLE_PATH=/usr/bin/chromium-browser
+
+# Set working directory
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install dependencies
+RUN npm ci --only=production
+
+# Copy application code
+COPY . .
+
+# Create non-root user
+RUN addgroup -g 1001 -S nodejs
+RUN adduser -S nextjs -u 1001
+
+# Change ownership of the app directory
+RUN chown -R nextjs:nodejs /app
+USER nextjs
+
+# Expose port
+EXPOSE 3000
+
+# Start the application
+CMD ["npm", "start"]