feat: Add PostgreSQL database infrastructure

- Add SQLAlchemy models for User, Translation, ApiKey, UsageLog, PaymentHistory
- Add database connection management with PostgreSQL/SQLite support
- Add repository layer for CRUD operations
- Add Alembic migration setup with initial migration
- Update auth_service to automatically use database when DATABASE_URL is set
- Update docker-compose.yml with PostgreSQL service and Redis (non-optional)
- Add database migration script (scripts/migrate_to_db.py)
- Update .env.example with database configuration

docker-compose.yml

@@ -4,6 +4,35 @@
 version: '3.8'
 
 services:
+  # ===========================================
+  # PostgreSQL Database
+  # ===========================================
+  postgres:
+    image: postgres:16-alpine
+    container_name: translate-postgres
+    restart: unless-stopped
+    environment:
+      - POSTGRES_USER=${POSTGRES_USER:-translate}
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD:-translate_secret_123}
+      - POSTGRES_DB=${POSTGRES_DB:-translate_db}
+      - PGDATA=/var/lib/postgresql/data/pgdata
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    networks:
+      - translate-network
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-translate} -d ${POSTGRES_DB:-translate_db}"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+      start_period: 10s
+    deploy:
+      resources:
+        limits:
+          memory: 512M
+        reservations:
+          memory: 128M
+
   # ===========================================
   # Backend API Service
   # ===========================================
@@ -14,23 +43,45 @@ services:
     container_name: translate-backend
     restart: unless-stopped
     environment:
+      # Database
+      - DATABASE_URL=postgresql+asyncpg://${POSTGRES_USER:-translate}:${POSTGRES_PASSWORD:-translate_secret_123}@postgres:5432/${POSTGRES_DB:-translate_db}
+      # Redis
+      - REDIS_URL=redis://redis:6379/0
+      # Translation Services
       - TRANSLATION_SERVICE=${TRANSLATION_SERVICE:-ollama}
       - OLLAMA_BASE_URL=${OLLAMA_BASE_URL:-http://ollama:11434}
       - OLLAMA_MODEL=${OLLAMA_MODEL:-llama3}
       - DEEPL_API_KEY=${DEEPL_API_KEY:-}
       - OPENAI_API_KEY=${OPENAI_API_KEY:-}
+      - OPENROUTER_API_KEY=${OPENROUTER_API_KEY:-}
+      # File Limits
       - MAX_FILE_SIZE_MB=${MAX_FILE_SIZE_MB:-50}
+      # Rate Limiting
       - RATE_LIMIT_REQUESTS_PER_MINUTE=${RATE_LIMIT_REQUESTS_PER_MINUTE:-60}
       - RATE_LIMIT_TRANSLATIONS_PER_MINUTE=${RATE_LIMIT_TRANSLATIONS_PER_MINUTE:-10}
-      - ADMIN_USERNAME=${ADMIN_USERNAME:-admin}
-      - ADMIN_PASSWORD=${ADMIN_PASSWORD:-changeme123}
-      - CORS_ORIGINS=${CORS_ORIGINS:-*}
+      # Admin Auth (CHANGE IN PRODUCTION!)
+      - ADMIN_USERNAME=${ADMIN_USERNAME}
+      - ADMIN_PASSWORD=${ADMIN_PASSWORD}
+      # Security
+      - JWT_SECRET=${JWT_SECRET}
+      - CORS_ORIGINS=${CORS_ORIGINS:-https://yourdomain.com}
+      # Stripe Payments
+      - STRIPE_SECRET_KEY=${STRIPE_SECRET_KEY:-}
+      - STRIPE_WEBHOOK_SECRET=${STRIPE_WEBHOOK_SECRET:-}
+      - STRIPE_STARTER_PRICE_ID=${STRIPE_STARTER_PRICE_ID:-}
+      - STRIPE_PRO_PRICE_ID=${STRIPE_PRO_PRICE_ID:-}
+      - STRIPE_BUSINESS_PRICE_ID=${STRIPE_BUSINESS_PRICE_ID:-}
     volumes:
       - uploads_data:/app/uploads
       - outputs_data:/app/outputs
       - logs_data:/app/logs
     networks:
       - translate-network
+    depends_on:
+      postgres:
+        condition: service_healthy
+      redis:
+        condition: service_healthy
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
       interval: 30s
@@ -117,7 +168,7 @@ services:
       - with-ollama
 
   # ===========================================
-  # Redis (Optional - For caching & sessions)
+  # Redis (Caching & Sessions)
   # ===========================================
   redis:
     image: redis:7-alpine
@@ -130,11 +181,9 @@ services:
       - translate-network
     healthcheck:
       test: ["CMD", "redis-cli", "ping"]
-      interval: 30s
-      timeout: 10s
-      retries: 3
-    profiles:
-      - with-cache
+      interval: 10s
+      timeout: 5s
+      retries: 5
 
   # ===========================================
   # Prometheus (Optional - Monitoring)
@@ -190,6 +239,8 @@ networks:
 # Volumes
 # ===========================================
 volumes:
+  postgres_data:
+    driver: local
   uploads_data:
     driver: local
   outputs_data: