Fix auth: auto-create customer, display name flow, OTP auto-verify

- Backend: getOrCreateCustomer with phone fallback for re-login
- Backend: PATCH /api/client/auth/profile for display name update
- Client app: AuthNeedsDisplayNameData state + SetDisplayNameScreen
- Client app: ApiClient.patch method
- Both apps: handle verificationCompleted for auto-verify (test numbers)
- Both apps: skip credential sign-in if already auto-verified
- Remove debug prints from mitra auth + OTP screens
- Fix ChatRequestNotifier.startListening skips when accepting

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/src/services/pairing.service.js

@@ -29,6 +29,7 @@ const notifyMitra = async (mitraId, data) => {
 // Send notification to customer via WebSocket, fall back to FCM if offline
 const notifyCustomer = async (customerId, data) => {
   const sent = sendToUser(UserType.CUSTOMER, customerId, data)
+  console.log(`[notifyCustomer] customerId=${customerId} type=${data.type} ws_sent=${sent}`)
   if (!sent) {
     if (data.type === WsMessage.PAIRED) {
       await sendPushNotification(UserType.CUSTOMER, customerId, {