Add complete infrastructure automation and documentation

- infrastructure/setup.sh: Master provisioning script for fresh Ubuntu servers
- infrastructure/docker-compose.yml: Production Docker Compose configuration
- infrastructure/.env.template: Environment variables template
- infrastructure/nginx/: Nginx configuration with security headers
- infrastructure/postfix/: Postfix + OpenDKIM email configuration
- infrastructure/README.md: Complete disaster recovery guide
- scripts/docfast-backup.sh: SQLite backup script with rotation

All services now fully reproducible with documented disaster recovery procedures.

infrastructure/docker-compose.yml

@@ -0,0 +1,41 @@
+version: "3.8"
+services:
+  docfast:
+    build: .
+    restart: unless-stopped
+    ports:
+      - "127.0.0.1:3100:3100"
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+    environment:
+      - API_KEYS=${API_KEYS}
+      - PORT=3100
+      - NODE_ENV=production
+      - STRIPE_SECRET_KEY=${STRIPE_SECRET_KEY}
+      - STRIPE_WEBHOOK_SECRET=${STRIPE_WEBHOOK_SECRET}
+      - BASE_URL=${BASE_URL:-https://docfast.dev}
+      - PRO_KEYS=${PRO_KEYS}
+      - SMTP_HOST=host.docker.internal
+      - SMTP_PORT=25
+      - DATABASE_HOST=172.17.0.1
+      - DATABASE_PORT=5432
+      - DATABASE_NAME=docfast
+      - DATABASE_USER=docfast
+      - DATABASE_PASSWORD=${DATABASE_PASSWORD:-docfast}
+      - POOL_SIZE=15
+      - BROWSER_COUNT=1
+      - PAGES_PER_BROWSER=15
+    volumes:
+      - docfast-data:/app/data
+    mem_limit: 2560m
+    cpus: 1.5
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:3100/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 40s
+
+volumes:
+  docfast-data:
+    driver: local