fix(voice): normalize WhatsApp wa_id before ContactInbox lookup

Inbound WhatsApp calls were matching contacts by stripping `+` from the
raw from_number, bypassing the BR/AR wa_id normalization that
Whatsapp::IncomingMessageServiceHelpers#processed_waid runs on the
messaging path. A wa_id whose webhook variant differs from the stored
normalized source_id (notably Brazil's added "9") would miss the
existing ContactInbox and create a fresh contact/conversation,
fragmenting history. Route the voice path through the same
Whatsapp::PhoneNumberNormalizationService so the lookup is consistent.

enterprise/app/services/voice/inbound_call_builder.rb

@@ -61,8 +61,13 @@ class Voice::InboundCallBuilder
   end
 
   # WhatsApp ContactInbox.source_id must be digits-only (the wa_id); Twilio accepts the +.
+  # Run BR/AR-style wa_id normalization (same path messaging uses) so an inbound call
+  # finds the existing ContactInbox instead of forking a new contact/conversation.
   def source_id_for_provider
-    provider == :whatsapp ? from_number.to_s.delete_prefix('+') : from_number
+    return from_number unless provider == :whatsapp
+
+    digits = from_number.to_s.delete_prefix('+')
+    Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact_by_provider(digits, :cloud)
   end
 
   def resolve_conversation!(contact, contact_inbox)

spec/enterprise/services/voice/inbound_call_builder_spec.rb

@@ -100,6 +100,31 @@ RSpec.describe Voice::InboundCallBuilder do
     end
   end
 
+  context 'when the WhatsApp wa_id needs Brazil normalization to match an existing ContactInbox' do
+    let(:whatsapp_channel) do
+      create(:channel_whatsapp, account: account, provider: 'whatsapp_cloud',
+                                provider_config: { 'phone_number_id' => '123', 'calling_enabled' => true },
+                                validate_provider_config: false, sync_templates: false)
+    end
+    let(:whatsapp_inbox) { whatsapp_channel.inbox }
+    let!(:stored_contact) { create(:contact, account: account, phone_number: '+5541988887777') }
+    let!(:stored_contact_inbox) do
+      create(:contact_inbox, contact: stored_contact, inbox: whatsapp_inbox, source_id: '5541988887777')
+    end
+
+    it 'reuses the contact via normalized wa_id rather than forking a new ContactInbox' do
+      call = described_class.perform!(
+        inbox: whatsapp_inbox,
+        from_number: '+554188887777',
+        call_sid: 'wacall_br_1',
+        provider: :whatsapp
+      )
+
+      expect(call.contact).to eq(stored_contact)
+      expect(call.conversation.contact_inbox).to eq(stored_contact_inbox)
+    end
+  end
+
   context 'when the inbox has lock_to_single_conversation enabled' do
     let!(:contact) { create(:contact, account: account, phone_number: from_number) }
     let!(:contact_inbox) { create(:contact_inbox, contact: contact, inbox: inbox, source_id: from_number) }