docs: add PM2 and Nginx prod setup for karate.ph.sokaris.link with www-data

README.md

@@ -96,6 +96,8 @@ cmd /c npm run build
 cmd /c npm start
 ```
 
+For production deployment instructions on Linux with **PM2**, **Nginx** (`karate.ph.sokaris.link`), and user **`www-data`**, see [`deploy/PM2_PRODUCTION_SETUP.md`](deploy/PM2_PRODUCTION_SETUP.md).
+
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 ## ⚙️ Configuration Guide