- VoiceCall bubble, voice.js helper, ConversationCard, and the store
mutation all switch from message.content_attributes.data to message.call.
- Message.vue gains a `call` prop that's provided through
useMessageContext for the bubble.
- UPDATE_MESSAGE_CALL_STATUS mutation now updates message.call.status,
matched by provider_call_id.
- content_attributes.data is still emitted by the backend for this
commit; backend-side trim lands in a follow-up.