Reconcile Chargebee invoices to Intacct invoices

**Objective:** For Chargebee customer `{chargebee-customer-id}`, compare Chargebee invoices from the last `{lookback-days}` days (default 90) with the Intacct invoices for the matching customer and list every difference.

**Step 1: Chargebee invoices**

Call `chargebee-get-invoice` (Chargebee server) with `customer-id` set to `{chargebee-customer-id}` and `date.from` set to the start of the window. Record each invoice id, date, total, amount due and status. Also call `chargebee-get-customer` (Chargebee server) with `id` to get the company name and email.

**Step 2: Intacct invoices**

Resolve the Intacct customer with `intacct-get-customer` (Intacct server) using `customer-id` `{intacct-customer-id}` if supplied, otherwise `customer-name.contains` set to the Chargebee company name. If it is ambiguous, list the candidates and stop. Then call `intacct-get-invoice` (Intacct server) with that `customer-id` and `invoice-date.from` set to the start of the window.

**Step 3: Match and report**

Match each Chargebee invoice to an Intacct invoice by invoice number appearing in the Intacct invoice number or reference, then by identical total and date within 3 days. Report three lists: in Chargebee only, in Intacct only, and matched with a different total or different paid/unpaid status (show both values and the difference). End with counts and the net total difference per currency.

**Rules & Guidelines:**

* `chargebee-get-invoice` and `chargebee-get-customer` are Chargebee tools; `intacct-get-customer` and `intacct-get-invoice` are Intacct tools.
* Read-only. Never call any Intacct create or update tool, for example `intacct-create-order-entry-document`.
* Never add amounts in different currencies together.

**Validation:**

* If either side returns no invoices, say which one and still report the other side's list.
* If invoice numbering differs between systems, say the match was by amount and date and flag it as lower confidence.