Add Client::browse_user (sends GetShareFileList, code 4, connecting first if needed via the same queue-and-flush path as search replies) and take_browse_result. A new SharedFileListResponseHandler parses the peer's code-5 reply into SharedDirectory entries, forwarded as ClientOperation::BrowseResult and stored per user. Verified end to end: a second real client browses a sharer and receives its file listing.