EmailAdapter._seen_uids accumulates every IMAP UID ever seen but
never removes any. A long-running gateway processing a high-volume
inbox would leak memory indefinitely — thousands of integers per day.
IMAP UIDs are monotonically increasing integers, so old UIDs are safe
to drop: new messages always have higher UIDs, and the IMAP UNSEEN
flag already prevents re-delivery regardless of our local tracking.
Fix adds _trim_seen_uids() which keeps only the most recent 1000 UIDs
(half of the 2000-entry cap) when the set grows too large. Called
automatically during connect() and after each fetch cycle.
Co-authored-by: memosr.eth <96793918+memosr@users.noreply.github.com>
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