Sign off a customer migration with only real differences listed

**Objective:** Confirm that Dynamics GP customers were migrated to Business Central with matching master data, for customer `{customer-id}` or, if that is empty, every active GP customer.

**Step 1: Read the GP customers**

Call `dynamics-gp-get-rm-customer` with `inactive` set to false, and with `customer-id` set to `{customer-id}` when it is given. Use a `max-records` large enough for the whole customer list (for example 5000). If exactly `max-records` rows come back, say the list may be truncated.

**Step 2: Read the BC customers**

Call `business-central-get-customer`, with `customer-number` set to `{customer-id}` when it is given, otherwise for the full list with the same `max-records`.

Match GP `customer-id` to BC `customer-number`. Compare them trimmed and case-insensitive: GP pads IDs with trailing spaces and BC stores them in upper case.

**Step 3: Compare each matched pair**

* customer-name vs name
* payment-terms-id vs payment-terms-code
* credit-limit-amount vs credit-limit
* salesperson-id vs salesperson-code
* city and state
* main-email-address vs email
* phone-1 vs phone-number, comparing digits only (GP stores phones as padded digit strings with an extension)
* hold = true in GP vs a non-blank blocked value in BC

**Step 4: Report**

Start with counts: matched with no differences, matched with differences, in GP but missing from BC, in BC with no GP match. Then a table of the differences (customer, field, GP value, BC value). List the missing customers separately. List the BC-only customers last and describe them as probably created after go-live, not as errors.

**Rules & Guidelines:**

* `dynamics-gp-get-rm-customer` is on the dynamics-gp server. `business-central-get-customer` is on the business-central server.
* This prompt is read-only. Do NOT call `business-central-create-customer`, `business-central-update-customer`, `dynamics-gp-rm-customer-add` or `dynamics-gp-rm-customer-update`.
* 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 GP returns no customers, stop and ask the user to confirm the GP company. If BC returns none, report that the customer migration has not run yet.
* Payment terms are often renamed during migration ("Net 30" becomes "30 DAYS"). When a whole set of customers differs the same way, report the pairing once as a mapping rather than once per customer.
* Treat a difference in case or surrounding spaces only as a match.