feat: Voice channel creation Flow (#11775)

This PR introduces a new channel type for voice conversations.

ref: #11481 

## Changes

- Add database migration for channel_voice table with phone_number and
provider_config
- Create Channel::Voice model with E.164 phone number validation and
Twilio config validation
- Add voice channel association to Account model
- Extend inbox helpers and types to support voice channels
- Add voice channel setup UI with Twilio configuration form
- Include voice channel in channel factory and list components
- Add API routes and store actions for voice channel creation
- Add comprehensive translations for voice channel management

---------

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>

spec/factories/channel/channel_voice.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :channel_voice, class: 'Channel::Voice' do
+    sequence(:phone_number) { |n| "+155512345#{n.to_s.rjust(2, '0')}" }
+    provider_config do
+      {
+        account_sid: "AC#{SecureRandom.hex(16)}",
+        auth_token: SecureRandom.hex(16),
+        api_key_sid: SecureRandom.hex(8),
+        api_key_secret: SecureRandom.hex(16)
+      }
+    end
+    account
+
+    after(:create) do |channel_voice|
+      create(:inbox, channel: channel_voice, account: channel_voice.account)
+    end
+  end
+end