feat(voice): wire Twilio voice flow through unified Call model

Moves call state off conversation.additional_attributes and
conversation.identifier onto first-class Call records, one per call.

- Call is the source of truth for status, direction, duration, started_at,
  accepted_by_agent, and conference_sid (in meta).
- Conference names key off Call.id (conf_account_{aid}_call_{cid}), so
  multiple calls on one conversation no longer collide. lock_to_single_conversation
  inboxes append each call as a new voice_call bubble in the existing thread.
- Agent identity on conference join webhooks is parsed from the Twilio
  ParticipantLabel (agent-{user_id}-account-{account_id}); stateless and
  independent of the /conference#create API call order.
- ConversationCard.vue derives the call badge from the latest voice_call
  message, not a denormalized cache on the conversation. Removes the stale
  "Call ended" state that lingered after subsequent text messages.

app/javascript/dashboard/components/widgets/conversation/ConversationCard.vue

@@ -95,10 +95,13 @@ const isInboxNameVisible = computed(() => !activeInbox.value);
 
 const lastMessageInChat = computed(() => getLastMessage(props.chat));
 
-const voiceCallData = computed(() => ({
-  status: props.chat.additional_attributes?.call_status,
-  direction: props.chat.additional_attributes?.call_direction,
-}));
+const voiceCallData = computed(() => {
+  const last = lastMessageInChat.value;
+  if (last?.content_type !== 'voice_call')
+    return { status: null, direction: null };
+  const data = last.content_attributes?.data ?? {};
+  return { status: data.status, direction: data.call_direction };
+});
 
 const inboxId = computed(() => props.chat.inbox_id);
 

app/javascript/dashboard/helper/voice.js

@@ -60,9 +60,10 @@ export function handleVoiceCallUpdated(commit, message, currentUserId) {
 
   callsStore.handleCallStatusChanged({ callSid, status, conversationId });
 
-  const callInfo = { conversationId, callStatus: status };
-  commit(types.UPDATE_CONVERSATION_CALL_STATUS, callInfo);
-  commit(types.UPDATE_MESSAGE_CALL_STATUS, callInfo);
+  commit(types.UPDATE_MESSAGE_CALL_STATUS, {
+    conversationId,
+    callStatus: status,
+  });
 
   const isNewCall =
     status === 'ringing' &&

app/javascript/dashboard/store/modules/conversations/index.js

@@ -307,19 +307,6 @@ export const mutations = {
     }
   },
 
-  [types.UPDATE_CONVERSATION_CALL_STATUS](
-    _state,
-    { conversationId, callStatus }
-  ) {
-    const chat = getConversationById(_state)(conversationId);
-    if (!chat) return;
-
-    chat.additional_attributes = {
-      ...chat.additional_attributes,
-      call_status: callStatus,
-    };
-  },
-
   [types.UPDATE_MESSAGE_CALL_STATUS](_state, { conversationId, callStatus }) {
     const chat = getConversationById(_state)(conversationId);
     if (!chat) return;

app/javascript/dashboard/store/modules/conversations/specs/mutations.spec.js

@@ -2,44 +2,6 @@ import { mutations } from '../index';
 import types from '../../../mutation-types';
 
 describe('#mutations', () => {
-  describe('#UPDATE_CONVERSATION_CALL_STATUS', () => {
-    it('does nothing if conversation is not found', () => {
-      const state = { allConversations: [] };
-      mutations[types.UPDATE_CONVERSATION_CALL_STATUS](state, {
-        conversationId: 1,
-        callStatus: 'ringing',
-      });
-      expect(state.allConversations).toEqual([]);
-    });
-
-    it('updates call_status preserving existing additional_attributes', () => {
-      const state = {
-        allConversations: [
-          { id: 1, additional_attributes: { other_attr: 'value' } },
-        ],
-      };
-      mutations[types.UPDATE_CONVERSATION_CALL_STATUS](state, {
-        conversationId: 1,
-        callStatus: 'in-progress',
-      });
-      expect(state.allConversations[0].additional_attributes).toEqual({
-        other_attr: 'value',
-        call_status: 'in-progress',
-      });
-    });
-
-    it('creates additional_attributes if it does not exist', () => {
-      const state = { allConversations: [{ id: 1 }] };
-      mutations[types.UPDATE_CONVERSATION_CALL_STATUS](state, {
-        conversationId: 1,
-        callStatus: 'completed',
-      });
-      expect(state.allConversations[0].additional_attributes).toEqual({
-        call_status: 'completed',
-      });
-    });
-  });
-
   describe('#UPDATE_MESSAGE_CALL_STATUS', () => {
     it('does nothing if conversation is not found', () => {
       const state = { allConversations: [] };

app/javascript/dashboard/store/mutation-types.js

@@ -51,7 +51,6 @@ export default {
   UPDATE_CONVERSATION_CUSTOM_ATTRIBUTES:
     'UPDATE_CONVERSATION_CUSTOM_ATTRIBUTES',
   UPDATE_CONVERSATION_LAST_ACTIVITY: 'UPDATE_CONVERSATION_LAST_ACTIVITY',
-  UPDATE_CONVERSATION_CALL_STATUS: 'UPDATE_CONVERSATION_CALL_STATUS',
   UPDATE_MESSAGE_CALL_STATUS: 'UPDATE_MESSAGE_CALL_STATUS',
   SET_MISSING_MESSAGES: 'SET_MISSING_MESSAGES',