feat: Fix Docker configuration and update documentation

- Fix nginx port mapping (12000:80) for single port exposure
- Remove backend port exposure (internal network only)
- Fix nginx configuration (remove invalid must-revalidate directive)
- Update README with correct setup instructions
- Update TODO.md with completed tasks and current status
- Application now running on http://localhost:12000 with production build

frontend/nginx.conf

@@ -8,7 +8,7 @@ server {
     gzip on;
     gzip_vary on;
     gzip_min_length 1024;
-    gzip_proxied expired no-cache no-store private must-revalidate auth;
+    gzip_proxied expired no-cache no-store private auth;
     gzip_types text/plain text/css text/xml text/javascript application/javascript application/xml+rss application/json;
 
     # Security headers