Enable CURL response decompression #277

Problem

The CURL client currently passes NULL to CURLOPT_ACCEPT_ENCODING, which means it does not advertise any supported compression encodings in the Accept-Encoding request header. As a result, servers never send compressed responses, leading to unnecessarily high bandwidth usage.

Proposed Solution

Change CURLOPT_ACCEPT_ENCODING from NULL to "" (empty string). Per the CURL documentation, passing an empty string causes CURL to:

1. Advertise all compression encodings it supports (e.g. gzip, deflate, br, zstd) via the Accept-Encoding header
2. Automatically decompress responses that use those encodings

This is a one-line change that can significantly reduce bandwidth for HTTP transfers.