- main.c: fix NULL pointer dereference in https_resp_cb() — req was
  used before NULL check, and FLOG also dereferenced NULL req->tx_id
- main.c: fix potential crash in get_host_from_uri() — strlen(host)
  was called before checking curl_url_get() return code, host could
  be NULL
- dns_server_tcp.c: fix data corruption on EAGAIN — sent += len was
  executed with len == -1 when EAGAIN/EWOULDBLOCK occurred, causing
  negative offset; added continue to skip the addition
- dns_server_tcp.c: fix format string mismatches in FLOG() calls —
  format had 2 specifiers but 4 arguments were passed (ipstr, port,
  strerror, errno); changed format to include all 4 arguments
- dns_server_tcp.c: fix typo 'listaning' -> 'listening'
- https_client.c: remove deprecated CURLPIPE_HTTP1 (since libcurl
  7.62.0), keep only CURLPIPE_MULTIPLEX