Prove payables carried over, vendor by vendor

**Objective:** Prove that open payables carried over from Dynamics GP to Business Central, for vendor `{vendor-id}` or, if that is empty, every GP vendor with a balance. Compare balances as of `{cutover-date}` (if that is empty, compare current balances and say so).

**Step 1: Read the GP balances**

Call `dynamics-gp-get-pm-vendor` with `vendor-id` set to `{vendor-id}` when it is given. Keep vendors whose current-balance is not zero.

**Step 2: Read the BC balances**

Call `business-central-get-vendor` for the same vendors and match GP `vendor-id` to BC `vendor-number`, trimmed and case-insensitive. When `{cutover-date}` is empty, use BC balance. When it is given, for any vendor whose balance differs, call `business-central-get-detailed-vendor-ledger` with `vendor-number` and `posting-date.to` set to `{cutover-date}` and use the sum of amount instead.

BC vendor ledger amounts are negative for money owed, while the BC vendor balance and the GP current-balance are positive. Flip the sign of the ledger sum before comparing.

**Step 3: Find the documents behind each difference**

For each vendor whose balances differ by more than 0.01:

1. Call `dynamics-gp-get-pm-payables-trx` with `vendor-id`, leaving out voided documents. Keep documents whose current-trx-amount is not zero.
2. Call `business-central-get-detailed-vendor-ledger` with `vendor-number`. Group its rows by vendor-ledger-entry-number and add up amount to get each entry's remaining amount.
3. Match GP document-number (the vendor's invoice number) to BC document-number. If that finds nothing, try the GP voucher-number, because some migrations post under the voucher.

**Step 4: Report**

A summary line: vendors compared, in balance, out of balance, total GP open AP, total BC open AP, net difference. Then, per out-of-balance vendor: GP balance, BC balance, difference, and the documents that explain it (open in GP but missing from BC, in BC but not open in GP, or open in both with different remaining amounts). Call out any open GP document due within the next 14 days that is missing from BC, since it will not be paid from BC.

**Rules & Guidelines:**

* `dynamics-gp-get-pm-vendor` and `dynamics-gp-get-pm-payables-trx` are on the dynamics-gp server. `business-central-get-vendor` and `business-central-get-detailed-vendor-ledger` are on the business-central server.
* This prompt is read-only. Do NOT call `business-central-create-journal-line`, `business-central-create-purchase-invoice`, `business-central-create-purchase-credit-memo` or `dynamics-gp-pm-payables-trx-add`.
* If either system has more than one company, ask the user which GP company and which BC company to use before the first call, and pass them as `company`.

**Validation:**

* If a GP vendor with a balance has no BC vendor, report it as a missing vendor with its full balance and do not look for documents.
* If the balances differ but no single document explains it, report the unexplained remainder rather than guessing.
* If BC has one entry per vendor whose amount equals the GP balance, the migration brought AP over at summary level; report the vendor as in balance at summary level.