Auto-complete digital-only orders

# SUMMARY
Digital-only paid orders should move to **Completed** immediately.

## DETAILS
This applies only when every line item in the order is virtual or downloadable. If any physical item is present, do not change status automatically. Add an order note when auto-completing so support can see the action in the timeline.

## RULES
– Complete the order immediately after payment if **all items are digital**.
– Add order note: **”Auto-completed (digital-only)”**.
– If **any physical item exists**, do **not** auto-complete.