Companion to the cherry-picked #74158 fix (non-streaming path):
- gateway/run.py: remove the identical history-dedup filter from
_deliver_media_from_response — the post-stream rescan is explicit-only
by design (#20834), so every MEDIA tag it finds is a deliberate
attachment request; drop the now-unused history_media_paths parameter
and its call-site plumbing.
- gateway/platforms/base.py: log suppressed bare local file paths on the
surviving local_files history dedup (#73771 observability ask).
- tests: focused regression file covering explicit resend delivery on
both lanes, current-turn tool-echo poisoning, surviving bare-path
dedup + its log line, and the upstream auto-append dedup invariant.
Fixes#73771