Reconcile Chargebee invoices to Rillet before month end

**Objective:** For Chargebee customer `{chargebee-customer-id}`, compare invoices on or after {date-from} (default: the last 90 days) between Chargebee and Rillet and report what is missing or different.

**Step 1: Read Chargebee invoices (chargebee server)**

Call `chargebee-get-customer` with `id` = {chargebee-customer-id} to get `email`, `company` and `preferred-currency`. Then call `chargebee-get-invoice` with `customer-id` = {chargebee-customer-id} and `date.from` = {date-from}. Keep `id`, `date`, `total`, `amount-due`, `status`, `po-number` and `currency-code`.

**Step 2: Find the Rillet customer (rillet server)**

Call `rillet-get-customer-emails` and match `email` to the Chargebee email (case-insensitive). Take its `customer-id`. If there is no email match, call `rillet-get-customers` and match `name` or `invoicing-name` to the Chargebee `company`. If there is still no match, report the customer as absent from Rillet and stop.

**Step 3: Read Rillet invoices (rillet server)**

Call `rillet-get-invoices` (no filters) and keep rows whose `customer-id` equals the Rillet id and whose `invoice-date` is on or after {date-from}. Keep `invoice-number`, `invoice-date`, `total`, `amount-due`, `status`, `purchase-order-number` and `currency`.

**Step 4: Match and compare**

Match each Chargebee invoice to a Rillet invoice by Chargebee `id` equal to `invoice-number`, then by `po-number` equal to `purchase-order-number`, then by same date and same total. Compare total, amount due and paid or open status.

**Step 5: Report**

Three lists: in Chargebee only, in Rillet only, and in both with a difference (show each side's values and the gap). End with counts and the total gap in amount due.

**Rules & Guidelines:**

* `chargebee-get-customer` and `chargebee-get-invoice` are on the chargebee server. `rillet-get-customer-emails`, `rillet-get-customers` and `rillet-get-invoices` are on the rillet server.
* Read-only. Do not call `rillet-add-invoice`, `rillet-update-invoice`, `rillet-add-invoice-payment` or any other Rillet write tool.

**Validation:**

* If currencies differ between the two sides, do not compare amounts; list the invoice under a currency mismatch heading.
* If either side returns no invoices, say so and report the other side's invoices as unmatched.
* Chargebee amounts may be in minor units on some accounts; if a total differs by an exact factor of 100, say so rather than reporting a large gap.