Change WooCommerce stock and prices on exactly the right SKU

**Objective:** For the item with SKU `{sku}`, set the stock quantity to `{stock-quantity}`, the regular price to `{regular-price}` and the sale price to `{sale-price}`. Change only the values that are given.

**Step 1: Find the item**

1. Call `woocommerce-get-product` with `sku` = `{sku}`.
2. If nothing matches, call `woocommerce-get-product-variation` with `sku` = `{sku}`. A match is a variation: keep `product-variation-id` and its parent `product-id`.
3. If a product matches and its `type` is `variable`, the SKU belongs to the parent, which has no price of its own. Call `woocommerce-get-product-variation` with `product-id`, list the variations with their SKUs, and stop so the user can choose one.
4. If nothing matches either read, say so and stop.

Keep the current `regular-price`, `sale-price`, `stock-quantity` and `stock-status`.

**Step 2: Check the changes**

* If `{stock-quantity}`, `{regular-price}` and `{sale-price}` are all empty, ask what to change and stop.
* Stock must be a whole number of 0 or more. If the item's `stock-quantity` is currently empty, stock is not tracked: ask whether to turn tracking on, and only then pass `manage-stock` true.
* Prices must be numbers above 0. The sale price must be below the regular price that will apply after the change.

**Step 3: Confirm**

Show a before and after table for each value that changes, and say which tool will write. Wait for an explicit yes.

**Step 4: Update**

* A simple product: call `woocommerce-update-product` once with `product-id` and only the changed values.
* A variation: call `woocommerce-update-product-variation` once with `variation-id` = the `product-variation-id`, `product-id` = the parent id, and only the changed values.

**Step 5: Verify and report**

Re-read the item with the same read tool used in Step 1, filtered by `sku`, and report the values before and after, including `stock-status` (setting stock above 0 on a tracked item moves it back to `instock`).

**Rules & Guidelines:**

* The only write tools this prompt may call are `woocommerce-update-product` or `woocommerce-update-product-variation`, once, never both.
* Do not call any other write tool (`woocommerce-add-order`, `woocommerce-update-order`, `woocommerce-add-order-note`, `woocommerce-send-order-details`, `woocommerce-add-refund`, `woocommerce-add-customer`, `woocommerce-update-customer`, `woocommerce-add-product`, `woocommerce-add-coupon`, `woocommerce-update-coupon`).
* Never pass `name`, `description`, `status` or `sku`; this prompt changes stock and prices only.

**Validation:**

* If the user's confirmation is anything other than a clear yes, stop without writing.
* If the update fails, report the error and stop.