Rank overdue Chargebee balances with their Dynamics GP position

**Objective:** List customers whose Chargebee invoices are overdue by more than `{min-amount}` (default 1) and show their Dynamics GP balance, credit limit and hold status, to prioritise collections. Use `{gp-company}` as the GP company when given.

**Step 1: Overdue invoices in Chargebee**

Call `chargebee-get-invoice` (chargebee server) with `amount-due.min` set to the minimum, and `due-date.to` set to today. Group by `customer-id`; sum amount-due per customer, and note the oldest due-date and dunning-status.

**Step 2: Dynamics GP position**

For each of the top 15 customers by amount due, call `dynamics-gp-get-rm-customer` (dynamics-gp server) with `customer-id`, falling back to `customer-name.contains` using the Chargebee company from `chargebee-get-customer`. Keep customer-balance, credit-limit-amount, hold and inactive.

**Step 3: Report**

A table ranked by Chargebee overdue amount: customer, overdue amount, oldest due date, dunning status, GP balance, credit limit, GP hold flag. Flag customers over their credit limit, customers on hold in GP who still have active Chargebee subscriptions, and customers with no GP record.

**Rules & Guidelines:**

* `chargebee-get-invoice` and `chargebee-get-customer` are on the chargebee server; `dynamics-gp-get-rm-customer` is on the dynamics-gp server.
* Read only. Do not call `dynamics-gp-rm-customer-update`, `dynamics-gp-rm-customer-note` or any other write tool.

**Validation:**

* If no overdue invoices exist, say so and stop.
* Show amounts with their currency; do not total across currencies.