"""Inbound media cache + outbound chunked streaming.

Inbound: ``media.upload`` (chunked binary frames) -> ``cache_*_from_bytes``
-> a ``media_ref`` the adapter attaches to the ``MessageEvent``. Enforces
size limit + sha256 + MIME re-sniff.

Outbound: ``send_*`` -> stage the file in the media cache, mint a
``media_id``, emit ``media.offer {media_id, mime, size, filename, kind}``;
serve bytes on ``media.pull`` as chunked binary frames. Delivery-path
security via ``validate_media_delivery_path``.

Reuses hermes ``cache_image/audio/video/document_from_bytes`` where possible.
All paths under ``get_hermes_home()/"android"/media``.

Milestone M4.
"""