Update backend env example for VPS-only deployment

backend/.env.example

@@ -1,11 +1,11 @@
-APP_ENV=development
+APP_ENV=production
 APP_HOST=127.0.0.1
 APP_PORT=3000
 PUBLIC_API_URL=https://api.example.ru
 PUBLIC_WS_URL=wss://api.example.ru/ws
 TRUST_PROXY=true
 
-DATABASE_PATH=./data/chat.sqlite
+DATABASE_PATH=/opt/raspi-chat/data/chat.sqlite
 
 ADMIN_ORIGIN=https://admin.example.ru
 WIDGET_ORIGIN=https://widget.example.ru
@@ -18,4 +18,8 @@ TELEGRAM_PROXY_PORT=9050
 TELEGRAM_PROXY_USERNAME=
 TELEGRAM_PROXY_PASSWORD=
 
-JWT_SECRET=change-me
+JWT_SECRET=change-me-to-long-random-string
+
+FRONTEND_DEPLOY_ENABLED=false
+FRONTEND_DEPLOY_MODE=manual-fastpanel
+FASTPANEL_SAFE_MODE=true