Implement zero-downtime deployment strategy

- Add rolling update mechanism for seamless deployments
- Start new container on port 3001, health check, then switch
- Preserve database and redis connections during updates
- Automatic fallback to fresh deployment if no current container
- Add advanced nginx load balancer configuration for future use
- Eliminate container name conflicts with proper cleanup
- Website stays online during deployments

nginx-zero-downtime.conf

@@ -0,0 +1,62 @@
+events {
+    worker_connections 1024;
+}
+
+http {
+    upstream portfolio_backend {
+        # Health check enabled upstream
+        server portfolio-app-1:3000 max_fails=3 fail_timeout=30s;
+        server portfolio-app-2:3000 max_fails=3 fail_timeout=30s;
+    }
+
+    # Health check endpoint
+    server {
+        listen 80;
+        server_name _;
+        
+        location /health {
+            access_log off;
+            return 200 "healthy\n";
+            add_header Content-Type text/plain;
+        }
+    }
+
+    # Main server
+    server {
+        listen 80;
+        server_name _;
+
+        # Proxy settings
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+
+        # Timeout settings
+        proxy_connect_timeout 5s;
+        proxy_send_timeout 60s;
+        proxy_read_timeout 60s;
+
+        # Buffer settings
+        proxy_buffering on;
+        proxy_buffer_size 4k;
+        proxy_buffers 8 4k;
+
+        # Main location
+        location / {
+            proxy_pass http://portfolio_backend;
+            
+            # Health check for upstream
+            proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
+            proxy_next_upstream_tries 2;
+            proxy_next_upstream_timeout 10s;
+        }
+
+        # Static files caching
+        location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+            proxy_pass http://portfolio_backend;
+            expires 1y;
+            add_header Cache-Control "public, immutable";
+        }
+    }
+}