One account review across Chargebee and NetSuite

**Objective:** Build an account review for the customer with email {email}, combining billing in Chargebee with receivables in NetSuite, looking back {lookback-days} days (default 180).

**Step 1: Chargebee side**

Call `chargebee-get-customer` with `email`. If several match, list them and stop. Take `id`. Call `chargebee-get-subscription` with `customer-id` (report status, mrr, next-billing-at, total-dues), `chargebee-get-invoice` with `customer-id` and `date.from`, and `chargebee-get-transaction` with `customer-id` and `date.from`.

**Step 2: NetSuite side**

Call `netsuite-get-customer` with `email`. If none match, report the customer as billing-only and skip to Step 3. Call `netsuite-get-invoice` with `customer-id` set to the NetSuite `internal-id` and `date.from`, `netsuite-get-aropenitem` with `customer` set to the customer name, and `netsuite-get-customerpayment` with `customer-id` and `date.from`.

**Step 3: Report**

Sections: identity (both ids, name, email), subscriptions and MRR, invoiced vs paid in each system, open balance in each system, and a short list of discrepancies (customer missing on one side, totals that disagree, past-due items).

**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 a side returns nothing, say so; do not invent figures.
* Report currencies as returned and do not convert.