- bing: www.bing.com 302-redirects to cn.bing.com and SearXNG engine
requests do not follow redirects, so it parsed the 178-byte redirect
page and returned 0 results without any error report. Point bing at
https://cn.bing.com to bypass the redirect.
- Raise outgoing request_timeout 3.0 -> 8.0 and max_request_timeout
4.0 -> 15.0. max_request_timeout overrides each engine's own timeout,
so 360search (timeout 20s) was still cut off at 4s.
- Enable duckduckgo (verified working) and disable baidu/sogou which
return 302 verification pages (baidu also hits a 1h CAPTCHA ban, and
sogou raises AttributeError on SXNG_Response.next_request).
- Document the diagnosis in the README FAQ.
