Function build_proxified_response 

pub fn build_proxified_response(part: BatchPart) -> BatchProxifiedResponse

Synthesize a BatchProxifiedResponse from a proxified batch part. Restores the upstream HTTP status from X-Scrapfly-Scrape-Status, merges upstream headers (after stripping the X-Scrapfly-Upstream- prefix) with Scrapfly metadata headers, and exposes the raw body.