feat: Add voice calling as a capability on Twilio SMS channel(Enterprise) (#13963)

Voice calling is now a capability on the existing TwilioSms rather than
a separate Voice model. A single Twilio phone number handles both SMS
and voice calls through one inbox.
Fixes
https://linear.app/chatwoot/issue/CW-6683/add-voice-calling-as-a-capability-on-twilio-sms-channel
and https://linear.app/chatwoot/issue/PLA-120/add-the-support-for-sms

**What changed**
- Replaced Channel::Voice with voice_enabled flag on Channel::TwilioSms
- Added voice_enabled, twiml_app_sid, api_key_secret columns to
channel_twilio_sms table
  - Dropped channel_voice table (no production data)
- All voice logic lives in Enterprise layer via
prepend_mod_with('Channel::TwilioSms')
- Added Voice settings tab on Twilio SMS inbox settings to
enable/disable voice
  - Validates Twilio number voice capability before provisioning
- Teardown service cleans up TwiML app and credentials when voice is
disabled
- Frontend voice detection uses isVoiceCallEnabled() /
getVoiceCallProvider() helpers — extensible to future providers
  - Gated by channel_voice feature flag

**How to test**

1. Enable feature flag:
Account.find(<id>).enable_features('channel_voice')
2. Create voice inbox: Inboxes → Voice tile → enter Twilio credentials →
verify incoming/outgoing calls and SMS work
3. Enable voice on existing SMS inbox: Inboxes → select Twilio SMS inbox
→ Voice tab → toggle on → provide API key credentials → verify calls
work
4. Disable voice: Voice tab → toggle off → verify TwiML app is deleted,
credentials cleared, SMS still works
5. Re-enable voice: Toggle on again → must provide api_key_secret again
→ new TwiML app provisioned

---------

Co-authored-by: Muhsin <12408980+muhsin-k@users.noreply.github.com>

app/javascript/dashboard/composables/spec/useInbox.spec.js

@@ -47,7 +47,11 @@ const mockStore = createStore({
             11: { id: 11, channel_type: INBOX_TYPES.API },
             12: { id: 12, channel_type: INBOX_TYPES.SMS },
             13: { id: 13, channel_type: INBOX_TYPES.INSTAGRAM },
-            14: { id: 14, channel_type: INBOX_TYPES.VOICE },
+            14: {
+              id: 14,
+              channel_type: INBOX_TYPES.TWILIO,
+              voice_enabled: true,
+            },
             15: { id: 15, channel_type: INBOX_TYPES.TIKTOK },
           };
           return inboxes[id] || null;
@@ -211,11 +215,11 @@ describe('useInbox', () => {
       });
       expect(wrapper.vm.isAnInstagramChannel).toBe(true);
 
-      // Test Voice
+      // Test Voice (Twilio with voice_enabled)
       wrapper = mount(createTestComponent(14), {
         global: { plugins: [mockStore] },
       });
-      expect(wrapper.vm.isAVoiceChannel).toBe(true);
+      expect(wrapper.vm.voiceCallEnabled).toBe(true);
 
       // Test Tiktok
       wrapper = mount(createTestComponent(15), {
@@ -274,7 +278,8 @@ describe('useInbox', () => {
         'isAnEmailChannel',
         'isAnInstagramChannel',
         'isATiktokChannel',
-        'isAVoiceChannel',
+        'voiceCallEnabled',
+        'voiceCallProvider',
       ];
 
       expectedProperties.forEach(prop => {

app/javascript/dashboard/composables/useInbox.js

@@ -1,7 +1,11 @@
 import { computed } from 'vue';
 import { useMapGetter } from 'dashboard/composables/store';
 import { useCamelCase } from 'dashboard/composables/useTransformKeys';
-import { INBOX_TYPES } from 'dashboard/helper/inbox';
+import {
+  INBOX_TYPES,
+  isVoiceCallEnabled,
+  getVoiceCallProvider,
+} from 'dashboard/helper/inbox';
 
 export const INBOX_FEATURES = {
   REPLY_TO: 'replyTo',
@@ -134,9 +138,9 @@ export const useInbox = (inboxId = null) => {
     return channelType.value === INBOX_TYPES.TIKTOK;
   });
 
-  const isAVoiceChannel = computed(() => {
-    return channelType.value === INBOX_TYPES.VOICE;
-  });
+  const voiceCallEnabled = computed(() => isVoiceCallEnabled(inbox.value));
+
+  const voiceCallProvider = computed(() => getVoiceCallProvider(inbox.value));
 
   return {
     inbox,
@@ -156,6 +160,7 @@ export const useInbox = (inboxId = null) => {
     isAnEmailChannel,
     isAnInstagramChannel,
     isATiktokChannel,
-    isAVoiceChannel,
+    voiceCallEnabled,
+    voiceCallProvider,
   };
 };