Adds a nested `call` object to the voice_call message JSON / push
payload so the frontend can read call state directly from message.call
instead of duplicating it in content_attributes.data.
- Message gains has_one :call (inverse of existing Call#belongs_to :message)
via enterprise module prepend.
- Message serializer (_message.json.jbuilder) emits a call block for
voice_call messages when the Call is linked.
- Message#push_event_data mirrors the payload into socket broadcasts.
- MessageFinder eager-loads the call (+ contact + inbox.channel) to
avoid N+1 when listing conversation messages.
- Call gains helper methods: display_status, from_number, to_number,
recording_url, push_event_data. These centralize the direction- and
status-aware derivations so jbuilder and push_event_data stay in sync.
Frontend continues to read content_attributes.data — this commit only
adds the new shape; a follow-up swaps readers to message.call.
Muhsin
5ce77eedbe