Find Shopify prices and costs that drifted from Dynamics GP

**Objective:** For products whose vendor or title contains `{product-filter}` (default: all, up to 100 variants), compare the Shopify selling price and unit cost with Dynamics GP, and report every variant where they differ by more than `{tolerance-percent}` percent (default 1).

**Step 1: Read the Shopify variants**

If `{product-filter}` is given, call `shopify-get-product` (Shopify server) with `title.contains` = `{product-filter}`, and if that returns nothing, with `vendor.contains` = `{product-filter}`. Then call `shopify-get-product-variant` (Shopify server) with each `product-id`. With no filter, call `shopify-get-product-variant` with `max-records` = 100. Keep `sku`, `title`, `price` and `inventory-item-id`.

For the cost, call `shopify-get-inventory-item` (Shopify server) with `sku` and read `cost`.

**Step 2: Read Dynamics GP for the same item numbers**

The Shopify `sku` is the Dynamics GP `item-number`. Call `dynamics-gp-get-iv-item` (Dynamics GP server) with `item-number` = the SKU for `current-cost` and `standard-cost`, and `dynamics-gp-get-iv-item-price` (Dynamics GP server) with the same `item-number` for `list-price`. Pass `company` = `{gp-company}` on both when it is given. If the price list has several rows, use the one for the item's selling unit of measure with the lowest `start-quantity`, and say which `price-level` you used.

**Step 3: Report**

A table: SKU, Variant, Shopify price, GP list price, Price difference %, Shopify cost, GP current cost, Cost difference %, and Margin at Shopify price (price minus GP current cost, as a percent of price). Only rows over the tolerance, largest difference first. Then list variants with no SKU and SKUs not found in GP.

**Rules & Guidelines:**

* Tools whose names start with shopify are on the Shopify server; tools whose names start with dynamics-gp are on the Dynamics GP server.
* This is read-only. Do NOT call `shopify-update-product`, `dynamics-gp-iv-item-update`, `dynamics-gp-iv-item-price-update` or `dynamics-gp-iv-item-price-add`.

**Validation:**

* If either price is zero or empty, show it as missing rather than computing a percentage.
* Assume both systems use the same currency; if GP's `currency-id` differs from the Shopify store currency, flag the row instead of comparing it.