See which overdue customers Chargebee is still chasing

**Objective:** List receivables in NetSuite that are overdue by more than {days-overdue} days (default 30) and show what Chargebee knows about each customer's dunning and subscription state.

**Step 1: Overdue items in NetSuite**

Call `netsuite-get-aropenitem` with `due-date.to` set to today minus {days-overdue} days. Keep items with a positive balance (`amount` minus `amount-applied`). Group by `customer` and total each. Keep the top {top-n} customers by amount (default 10).

**Step 2: Find each customer in Chargebee**

For each customer, call `netsuite-get-customer` with `name` to get `email`. Then call `chargebee-get-customer` with `email`. If not found, mark "not in Chargebee". Otherwise call `chargebee-get-invoice` with `customer-id` and `status` payment_due and report `dunning-status` and `amount-due`, and `chargebee-get-subscription` with `customer-id` for `status` and `next-billing-at`.

**Step 3: Report**

Table: customer, NetSuite overdue total, oldest due-date, Chargebee amount due, dunning-status, subscription status. Flag customers overdue in NetSuite with no open Chargebee invoice (ledger and billing disagree) and customers whose dunning has stopped.

**Rules & Guidelines:**

* Tools whose names start with netsuite are on the netsuite server; tools whose names start with chargebee are on the chargebee server. Both servers must be connected.
* Read-only: never call any NetSuite add or update tool (for example `netsuite-add-invoice`, `netsuite-add-customerpayment`, `netsuite-update-invoice`, `netsuite-update-customer`). Chargebee has no write tools here. Report differences only; never fix them.

**Validation:**

* If NetSuite has no overdue items, say so and stop.
* If a customer name matches several NetSuite customers, show the ambiguity instead of picking one.