Check Ramp statements, cashback and repayments before close

**Objective:** Review card statements that started in the last {months-back} months (default 3), with their cashback and repayments, for the period close.

**Step 1: Statements**

Call `ramp-get-statement` with `start-date.from` set to the window start. For each, note opening balance, charges, credits, payments and ending balance.

**Step 2: Check the arithmetic**

Opening balance plus charges minus credits minus payments should equal ending balance. Flag any statement where it does not, by the difference.

**Step 3: Cashback and repayments**

Call `ramp-get-cashback` with `created-at.from` set to the window start. Call `ramp-get-repayment` with `repaid-at.from` set to the window start. Flag items whose sync status is not synced and repayments not in a completed status.

**Step 4: Report**

One table per statement with the arithmetic result, then cashback and repayment tables, then the open items.

**Rules & Guidelines:**

* Read only. Do not call any write tool.
* Never combine amounts in different currencies.

**Validation:**

* If `{months-back}` is not a positive whole number, use 3.
* If no statements are returned, say so and stop.