docs: add all available environment variables to Docker Compose example

Listed all env vars with descriptions and defaults, commented out for easy enabling.
Users can now discover and configure all options without checking separate docs.

README.md

@@ -89,8 +89,30 @@ services:
     volumes:
       - pulse_data:/data
     environment:
-      # Optional: specify your LAN subnet for auto-discovery
-      # - DISCOVERY_SUBNET=192.168.1.0/24
+      # Network discovery
+      # - DISCOVERY_SUBNET=192.168.1.0/24  # Auto-discovery subnet (default: auto-detect)
+      
+      # Ports
+      # - PORT=7655                         # Backend port (default: 7655)
+      # - FRONTEND_PORT=7655                # Frontend port (default: 7655)
+      
+      # Security
+      # - API_TOKEN=your-secure-token       # API authentication token
+      # - ALLOW_UNPROTECTED_EXPORT=false    # Allow export without auth (default: false)
+      
+      # Polling & timeouts
+      # - POLLING_INTERVAL=5                # Seconds between node checks (default: 5)
+      # - CONNECTION_TIMEOUT=10             # Connection timeout in seconds (default: 10)
+      
+      # Updates
+      # - UPDATE_CHANNEL=stable             # Update channel: stable or rc (default: stable)
+      # - AUTO_UPDATE_ENABLED=true          # Enable auto-updates (default: true)
+      # - AUTO_UPDATE_CHECK_INTERVAL=24     # Hours between update checks (default: 24)
+      # - AUTO_UPDATE_TIME=03:00            # Time to install updates HH:MM (default: 03:00)
+      
+      # CORS & logging
+      # - ALLOWED_ORIGINS=*                 # CORS allowed origins (default: *)
+      # - LOG_LEVEL=info                    # Log level: debug/info/warn/error (default: info)
     restart: unless-stopped
 
 volumes: