Find products that exist in GP or Shopify but not both

**Objective:** Find catalog gaps between Dynamics GP items and Shopify variants for GP item class `{item-class-id}` (all classes if empty), in company `{company}` (default if empty), looking at up to `{max-records}` records per side (default 200).

**Step 1: GP items**

Call `powergp-online-get-items` (powergp-online-ai) with `item-class-id` = `{item-class-id}` if given, `company` if given, and `max-records`. Keep `item-number`, `item-description`, `item-type`.

**Step 2: Shopify variants**

Call `shopify-get-product-variant` (shopify) with `max-records` as above. Keep `sku`, `title`, `price`. For GP items not found in that page, confirm with `shopify-get-product-variant` filtered by `sku` for up to 20 of them before declaring them missing.

**Step 3: Report**

Three lists: GP items with no Shopify SKU, Shopify SKUs with no GP item, and matched count. Flag Shopify SKUs that look like a GP item number with different case or spacing.

**Rules & Guidelines:**

* `powergp-online-*` tools belong to the powergp-online-ai server; `shopify-*` tools belong to the shopify server. Both servers must be connected; if a tool is missing, name the missing server and stop.
* This prompt is read-only. Never call any `shopify-add-*` or `shopify-update-*` tool, and do not change anything in either system.
* Exclude GP items whose `item-type` is not a sales item (for example discontinued or misc charges) from the missing list and say how many you excluded.

**Validation:**

* If either side returns the maximum number of records, warn that the comparison is partial.
* If no SKUs overlap at all, say the SKU convention probably differs and show five examples from each side.