Curl Server doesn't support User-Agent

[jdordonezn]

Regardless of whether you pass a User-Agent header it is overwriting:

      headers: {
        ...headers,
        'User-Agent': '@mcp-get-community/server-curl'
      }

For this value to be the default, the order of lines 53 and 54 must be reversed, because the last statement is the one that has priority.