🔧 Fix zero-downtime deployment issues

- Fix Dockerfile standalone build path from /app/.next/standalone/gitea/portfolio to /app/.next/standalone/app
- Fix nginx configuration by removing conflicting server blocks
- Consolidate health check and main proxy into single server block
- Ensure proper load balancing between portfolio-app-1 and portfolio-app-2

✅ Deployment now working successfully with:
- Application running on both instances (healthy)
- Database and Redis running (healthy)
- Nginx load balancer working
- Health endpoints accessible
- Main portfolio site accessible at http://localhost/

nginx-zero-downtime.conf

@@ -9,18 +9,6 @@ http {
         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;
@@ -42,6 +30,13 @@ http {
         proxy_buffer_size 4k;
         proxy_buffers 8 4k;
 
+        # Health check endpoint
+        location /health {
+            access_log off;
+            return 200 "healthy\n";
+            add_header Content-Type text/plain;
+        }
+
         # Main location
         location / {
             proxy_pass http://portfolio_backend;