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>

enterprise/app/models/channel/voice.rb

@@ -0,0 +1,64 @@
+# == Schema Information
+#
+# Table name: channel_voice
+#
+#  id                    :bigint           not null, primary key
+#  additional_attributes :jsonb
+#  phone_number          :string           not null
+#  provider              :string           default("twilio"), not null
+#  provider_config       :jsonb            not null
+#  created_at            :datetime         not null
+#  updated_at            :datetime         not null
+#  account_id            :integer          not null
+#
+# Indexes
+#
+#  index_channel_voice_on_account_id    (account_id)
+#  index_channel_voice_on_phone_number  (phone_number) UNIQUE
+#
+class Channel::Voice < ApplicationRecord
+  include Channelable
+
+  self.table_name = 'channel_voice'
+
+  validates :phone_number, presence: true, uniqueness: true
+  validates :provider, presence: true
+  validates :provider_config, presence: true
+
+  # Validate phone number format (E.164 format)
+  validates :phone_number, format: { with: /\A\+[1-9]\d{1,14}\z/ }
+
+  # Provider-specific configs stored in JSON
+  validate :validate_provider_config
+
+  EDITABLE_ATTRS = [:phone_number, :provider, { provider_config: {} }].freeze
+
+  def name
+    "Voice (#{phone_number})"
+  end
+
+  def messaging_window_enabled?
+    false
+  end
+
+  private
+
+  def validate_provider_config
+    return if provider_config.blank?
+
+    case provider
+    when 'twilio'
+      validate_twilio_config
+    end
+  end
+
+  def validate_twilio_config
+    config = provider_config.with_indifferent_access
+    required_keys = %w[account_sid auth_token api_key_sid api_key_secret]
+
+    required_keys.each do |key|
+      errors.add(:provider_config, "#{key} is required for Twilio provider") if config[key].blank?
+    end
+  end
+end
+

enterprise/app/models/enterprise/concerns/account.rb

@@ -11,5 +11,6 @@ module Enterprise::Concerns::Account
     has_many :captain_documents, dependent: :destroy_async, class_name: 'Captain::Document'
 
     has_many :copilot_threads, dependent: :destroy_async
+    has_many :voice_channels, dependent: :destroy_async, class_name: '::Channel::Voice'
   end
 end