feat(voice): embed Call in voice_call message payload

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.

app/finders/message_finder.rb

@@ -11,7 +11,9 @@ class MessageFinder
   private
 
   def conversation_messages
-    @conversation.messages.includes(:attachments, :sender, sender: { avatar_attachment: [:blob] })
+    scope = @conversation.messages.includes(:attachments, :sender, sender: { avatar_attachment: [:blob] })
+    scope = scope.includes(call: [:contact, { inbox: :channel }]) if Message.reflect_on_association(:call)
+    scope
   end
 
   def messages

app/models/message.rb

@@ -152,9 +152,14 @@ class Message < ApplicationRecord
     )
     data[:echo_id] = echo_id if echo_id.present?
     data[:attachments] = attachments.map(&:push_event_data) if attachments.present?
+    data[:call] = call.push_event_data if voice_call? && respond_to?(:call) && call.present?
     merge_sender_attributes(data)
   end
 
+  def voice_call?
+    content_type == 'voice_call'
+  end
+
   def conversation_push_event_data
     {
       assignee_id: conversation.assignee_id,

app/views/api/v1/models/_message.json.jbuilder

@@ -12,3 +12,23 @@ json.private message.private
 json.source_id message.source_id
 json.sender message.sender.push_event_data if message.sender
 json.attachments message.attachments.map(&:push_event_data) if message.attachments.present?
+
+if message.content_type == 'voice_call' && message.respond_to?(:call) && message.call.present?
+  call = message.call
+  json.call do
+    json.id call.id
+    json.provider_call_id call.provider_call_id
+    json.provider call.provider
+    json.direction call.direction
+    json.status call.display_status
+    json.duration_seconds call.duration_seconds
+    json.conference_sid call.conference_sid
+    json.accepted_by_agent_id call.accepted_by_agent_id
+    json.started_at call.started_at&.to_i
+    json.ended_at call.ended_at
+    json.from_number call.from_number
+    json.to_number call.to_number
+    json.recording_url call.recording_url
+    json.transcript call.transcript
+  end
+end

enterprise/app/models/call.rb

@@ -45,7 +45,7 @@ class Call < ApplicationRecord
   belongs_to :inbox
   belongs_to :conversation
   belongs_to :contact
-  belongs_to :message, optional: true
+  belongs_to :message, optional: true, inverse_of: :call
   belongs_to :accepted_by_agent, class_name: 'User', optional: true
 
   has_one_attached :recording
@@ -70,4 +70,41 @@ class Call < ApplicationRecord
   def display_direction
     DISPLAY_DIRECTION[direction]
   end
+
+  def display_status
+    status.to_s.tr('_', '-')
+  end
+
+  def from_number
+    incoming? ? contact.phone_number : inbox.channel&.phone_number
+  end
+
+  def to_number
+    incoming? ? inbox.channel&.phone_number : contact.phone_number
+  end
+
+  def recording_url
+    return nil unless recording.attached?
+
+    Rails.application.routes.url_helpers.rails_blob_url(recording)
+  end
+
+  def push_event_data
+    {
+      id: id,
+      provider_call_id: provider_call_id,
+      provider: provider,
+      direction: direction,
+      status: display_status,
+      duration_seconds: duration_seconds,
+      conference_sid: conference_sid,
+      accepted_by_agent_id: accepted_by_agent_id,
+      started_at: started_at&.to_i,
+      ended_at: ended_at,
+      from_number: from_number,
+      to_number: to_number,
+      recording_url: recording_url,
+      transcript: transcript
+    }
+  end
 end

enterprise/app/models/enterprise/message.rb

@@ -1,4 +1,12 @@
 module Enterprise::Message
+  def self.prepended(base)
+    base.class_eval do
+      has_one :call, class_name: 'Call', foreign_key: :message_id, dependent: :nullify, inverse_of: :message
+
+      scope :with_call, -> { includes(call: [:contact, { inbox: :channel }]) }
+    end
+  end
+
   private
 
   def mark_pending_conversation_as_open_for_human_response