* fix(whatsapp): use payload filename for documents to avoid Content-Disposition parsing issues
When receiving documents via the WhatsApp Cloud API, filenames with
spaces or special characters were mangled due to the Down gem's
case-sensitive Content-Disposition header parsing. Now uses the
filename from the WhatsApp message payload when available, falling
back to Content-Disposition for other attachment types.
* fix: scope payload filename preference to document messages only
* fix: revert document-only scope, apply payload filename for all attachment types
84242aae7b