_handle_media_message had the same gap as _handle_text_message: it didn't
set user_id/user_name or any reply_to_* fields on MessageEvent. A user
replying to a photo/video/audio in Matrix got null sender metadata and
null reply context — the exact bug PR #80293 fixes for text messages.
Mirrors the text handler's reply fallback parsing + sender propagation
into the media handler, and adds a test covering a media reply event.
Also fixes test env mutation: _make_adapter now accepts monkeypatch
and uses monkeypatch.setenv() instead of bare os.environ assignment,
preventing env var leakage across tests in the same xdist worker.
kshitij
e8511efe75