fix(voice): address PR #14356 review feedback

- Return 422 (not 200) from `WhatsappCallsController#initiate` permission
  branch so clients can't mistake the opt-in template path for a
  successful dial. Body shape unchanged (`{ status: ... }`).
- Drop the `file.attached?` guard from `enqueue_audio_transcription`.
  The social-media ingest path (Messages::Messenger::MessageBuilder)
  saves the Attachment before attaching the blob, and the guard was
  silently dropping transcription for those audio messages.
  AudioTranscriptionJob already has retry_on FileNotFoundError to ride
  out the create-then-attach race.

enterprise/app/controllers/api/v1/accounts/whatsapp_calls_controller.rb

@@ -132,7 +132,10 @@ class Api::V1::Accounts::WhatsappCallsController < Api::V1::Accounts::BaseContro
 
     return render_could_not_create_error(I18n.t('errors.whatsapp.calls.permission_request_failed')) if status == 'failed'
 
-    render json: { status: status }
+    # 422 (not 200) so any client treating 2xx as "call placed" can't mistake
+    # the permission-template path for a successful dial. The FE composable
+    # detects this status and surfaces the banner instead of throwing.
+    render json: { status: status }, status: :unprocessable_entity
   end
 
   def permission_request_throttled?

enterprise/app/models/enterprise/concerns/attachment.rb

@@ -14,8 +14,10 @@ module Enterprise::Concerns::Attachment
 
   def enqueue_audio_transcription
     return unless file_type.to_sym == :audio
-    return unless file.attached?
 
+    # No file.attached? guard: the social-media ingest path saves the
+    # Attachment before attaching the blob. AudioTranscriptionJob retries
+    # on ActiveStorage::FileNotFoundError to ride out that race.
     Messages::AudioTranscriptionJob.perform_later(id)
   end