Stop paying an invoice twice across a system cutover

**Objective:** Tell the user whether vendor `{vendor-id}`'s invoice `{invoice-number}` (or, when no number is given, an invoice for `{amount}`) is safe to enter and pay in Intacct, or was already handled in Dynamics GP.

**Step 1: Look in GP**

Call `dynamics-gp-get-pm-payables-trx` with `vendor-id` = `{vendor-id}`, and `document-number` = `{invoice-number}` when given; otherwise `document-amount.min` and `document-amount.max` both = `{amount}`. Include voided documents and note them. If nothing matches, retry without the number filter and compare numbers yourself, ignoring case, spaces, dashes and leading zeros.

For every match, call `dynamics-gp-get-pm-payables-apply` with `apply-to-document-number` = its `document-number` to find payments applied to it (payment `document-number`, `payment-date`, `applied-amount`).

**Step 2: Look in Intacct**

Call `intacct-get-bill` with `vendor-id` = `{vendor-id}` and `bill-number` = `{invoice-number}` (or the amount filters), then with `vendor-id` alone if needed, comparing the same way. If the vendor id is not found in Intacct, look it up with `intacct-get-vendor` by the GP `vendor-name`. For bills found, check `total-paid` and call `intacct-get-ap-payment` for the vendor around the bill's dates.

**Step 3: Verdict**

Give one verdict first, then the evidence:
* **SAFE**: not in GP, not in Intacct.
* **PAID IN GP**: recorded and paid in GP. Do not pay again. Show the payment number, date and amount.
* **OPEN IN GP**: recorded in GP, not paid. It should have migrated as an open bill; check it is in Intacct once only.
* **ALREADY IN INTACCT**: already entered in Intacct. Show state and amount paid.
* **IN BOTH, CHECK FOR DUPLICATE**: paid in GP and open in Intacct, or open in both.

**Rules & Guidelines:**

* Tools prefixed dynamics-gp- are on the dynamics-gp MCP server. Tools prefixed intacct- are on the intacct MCP server. Both servers must be connected; if a tool from either is missing, say which server is not connected and stop.
* Pass `{gp-company}` as `company` on every dynamics-gp- call (empty means the default GP company). Use the default Intacct company; if the Intacct side holds several entities and it is not clear which one received this GP company, ask before starting.
* Read only. Do NOT call `dynamics-gp-pm-payables-trx-add`, `intacct-create-recurring-bill`, `intacct-create-charge-card-transaction` or `intacct-update-vendor`.

**Validation:**

* If neither `{invoice-number}` nor `{amount}` is given, ask for one before searching.
* A near match (same amount, different number, within 30 days) is worth showing as "possible match", but never as the verdict on its own.