list and search now fetch BODY.PEEK[HEADER] + BODYSTRUCTURE instead of the
whole RFC822 message, so listing a large mailbox no longer downloads every
message body and attachment. Header parsing reuses the same go-message path
(RFC2047 decoding/formatting preserved); has_attachments is derived from the
BODYSTRUCTURE tree. FetchFull keeps fetching the full message for get.
Validated end-to-end against a live IMAP account: list/search/get output
identical to the prior full-fetch behaviour, has_attachments correct.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
steve