feat(waitlist): queue position on the customer manage page

A waitlisted customer saw only a bare status — worse, the badge fell
back to "Pending" for both waitlisted and cancelled states. The view
now carries a 1-based waitlistPosition (earlier-created waitlisted
bookings on the session + 1) and the page renders a warning-tone
notice with the queue spot and auto-promotion explanation, in CS/EN.
Also fixed the badge's nonexistent --danger-soft/--warning-soft tokens.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/bookings/customer_service.go

@@ -108,17 +108,23 @@ func (s *CustomerService) GetBookingByReference(ctx context.Context, reference s
 
 	serviceName, locationName := s.descriptors(ctx, booking)
 
+	position := 0
+	if booking.Status == "waitlisted" && booking.ClassSessionID != nil {
+		position, _ = s.repo.GetWaitlistPosition(ctx, *booking.ClassSessionID, booking.ID)
+	}
+
 	return domain.CustomerBookingView{
-		Reference:     booking.Reference,
-		CustomerName:  booking.CustomerName,
-		CustomerEmail: booking.CustomerEmail,
-		Service:       serviceName,
-		BusinessName:  tenant.Name,
-		StartsAt:      booking.StartsAt,
-		EndsAt:        booking.EndsAt,
-		Location:      locationName,
-		Status:        booking.Status,
-		Notes:         booking.Notes,
+		Reference:        booking.Reference,
+		CustomerName:     booking.CustomerName,
+		CustomerEmail:    booking.CustomerEmail,
+		Service:          serviceName,
+		BusinessName:     tenant.Name,
+		StartsAt:         booking.StartsAt,
+		EndsAt:           booking.EndsAt,
+		Location:         locationName,
+		Status:           booking.Status,
+		Notes:            booking.Notes,
+		WaitlistPosition: position,
 	}, nil
 }