server {
    listen 80;
    server_name _;
    root /usr/share/nginx/html;
    index index.html;

    # Security headers
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; media-src 'self' blob:; connect-src 'self'; font-src 'self';" always;
    add_header Permissions-Policy "camera=(), microphone=(), geolocation=()" always;

    # API proxy to backend
    location /api/ {
        resolver 127.0.0.11 valid=10s;
        set $backend http://backend:8000;
        proxy_pass $backend;
        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;

        # Large file uploads
        client_max_body_size 500M;
        proxy_request_buffering off;
        proxy_read_timeout 600s;
    }

    # SPA fallback
    location / {
        try_files $uri $uri/ /index.html;
    }
}