feat: Add SaaS robustness middleware - Rate limiting with token bucket and sliding window algorithms - Input validation (file, language, provider) - Security headers middleware (CSP, XSS protection, etc.) - Automatic file cleanup with TTL tracking - Memory and disk monitoring - Enhanced health check and metrics endpoints - Request logging with unique IDs

.env.example

@@ -1,5 +1,11 @@
-# Translation Service Configuration
-TRANSLATION_SERVICE=google  # Options: google, deepl, libre, ollama
+# Document Translation API - Environment Configuration
+# Copy this file to .env and configure your settings
+
+# ============== Translation Services ==============
+# Default provider: google, ollama, deepl, libre, openai
+TRANSLATION_SERVICE=google
+
+# DeepL API Key (required for DeepL provider)
 DEEPL_API_KEY=your_deepl_api_key_here
 
 # Ollama Configuration (for LLM-based translation)
@@ -7,7 +13,58 @@ OLLAMA_BASE_URL=http://localhost:11434
 OLLAMA_MODEL=llama3
 OLLAMA_VISION_MODEL=llava
 
-# API Configuration
+# ============== File Limits ==============
+# Maximum file size in MB
 MAX_FILE_SIZE_MB=50
-UPLOAD_DIR=./uploads
-OUTPUT_DIR=./outputs
+
+# ============== Rate Limiting (SaaS) ==============
+# Enable/disable rate limiting
+RATE_LIMIT_ENABLED=true
+
+# Request limits
+RATE_LIMIT_PER_MINUTE=30
+RATE_LIMIT_PER_HOUR=200
+
+# Translation-specific limits
+TRANSLATIONS_PER_MINUTE=10
+TRANSLATIONS_PER_HOUR=50
+MAX_CONCURRENT_TRANSLATIONS=5
+
+# ============== Cleanup Service ==============
+# Enable automatic file cleanup
+CLEANUP_ENABLED=true
+
+# Cleanup interval in minutes
+CLEANUP_INTERVAL_MINUTES=15
+
+# File time-to-live in minutes
+FILE_TTL_MINUTES=60
+INPUT_FILE_TTL_MINUTES=30
+OUTPUT_FILE_TTL_MINUTES=120
+
+# Disk space warning thresholds (GB)
+DISK_WARNING_THRESHOLD_GB=5.0
+DISK_CRITICAL_THRESHOLD_GB=1.0
+
+# ============== Security ==============
+# Enable HSTS (only for HTTPS deployments)
+ENABLE_HSTS=false
+
+# CORS allowed origins (comma-separated)
+CORS_ORIGINS=*
+
+# Maximum request size in MB
+MAX_REQUEST_SIZE_MB=100
+
+# Request timeout in seconds
+REQUEST_TIMEOUT_SECONDS=300
+
+# ============== Monitoring ==============
+# Log level: DEBUG, INFO, WARNING, ERROR
+LOG_LEVEL=INFO
+
+# Enable request logging
+ENABLE_REQUEST_LOGGING=true
+
+# Memory usage threshold (percentage)
+MAX_MEMORY_PERCENT=80