refactor: remove old ecosystem configuration files and replace with JSON format

backend/ecosystem.config.js

@@ -1,14 +0,0 @@
-module.exports = {
-  apps: [{
-    name: 'portfolio-backend', // A name for your application in PM2
-    script: 'server.js',      // The path to the script PM2 will run
-    cwd: `${process.env.DEPLOY_PATH}/backend`, // Current working directory for the script
-    instances: 1,             // Run a single instance of the application
-    autorestart: true,        // Automatically restart if the app crashes
-    watch: false,             // Do NOT watch for file changes in production
-    max_memory_restart: '256M', // Restart if it uses more than 256MB of RAM
-    env: {
-      NODE_ENV: 'production', // Set the environment to production
-    }
-  }]
-};

backend/ecosystem.config.json

@@ -0,0 +1,12 @@
+{
+  "apps": [{
+    "name": "portfolio-backend",
+    "script": "server.js",
+    "instances": 1,
+    "autorestart": true,
+    "watch": false,
+    "env": {
+      "NODE_ENV": "production"
+    }
+  }]
+}