The cron scheduler delivery path passed raw text including MEDIA: tags
to _send_to_platform(), so media attachments were delivered as literal
text instead of actual files. The send function already supports
media_files= but the cron path never used it.
Now calls BasePlatformAdapter.extract_media() to split media paths
from text before sending, matching the gateway's normal message flow.
Salvaged from PR #4877 by robert-hoffmann.
3d08a2fa1b