[Fix] Encode redirect URLs to handle unencoded spaces and special characters

[Fix] Encode redirect URLs to handle unencoded spaces and special characters

This fixes issue #5525 where url_redirector fails when redirect Location
headers contain unencoded spaces or other special characters.

The http_parser_parse_url() function strictly requires percent-encoded URLs
per RFC 3986, but many servers send Location headers with unencoded spaces.

Changes:
- Add encode_url_for_redirect() function to percent-encode problematic characters
- Apply encoding to redirect Location headers before creating URL objects
- Preserve already-encoded sequences (no double-encoding)
- Log warnings for URLs that fail even after encoding

The fix is conservative - only encodes characters that http_parser rejects,
maintaining full backward compatibility with properly formatted URLs.

Closes: #5525