Check Shopify stock behind every product in a Mailchimp campaign

**Objective:** For the Mailchimp campaign named `{campaign-name}`, find every Shopify product page it linked to, and flag any variant whose stock is at or below `{low-stock-threshold}` (default 5).

**Step 1: Campaign links in Mailchimp**

Call `mailchimp-get-campaign` with `title.contains` = `{campaign-name}`. If it matches more than one campaign, list them with `send-date` and stop. Note `campaign-id`, `title`, `status` and `send-date`. Then call `mailchimp-get-campaign-click` with `campaign-id` and `url.contains` = /products/. Keep `url`, `clicks` and `unique-clicks`.

**Step 2: Product handles**

From each URL take the path segment directly after /products/, dropping any query string, fragment or trailing slash; that is the Shopify product handle. Merge URLs that give the same handle and add their clicks.

**Step 3: Stock in Shopify**

For each handle, call `shopify-get-product` with `handle`. If nothing comes back, mark the link "no matching Shopify product". Otherwise note `product-id` and `title`, and call `shopify-get-product-variant` with `product-id`. For each variant note `title`, `sku`, `inventory-quantity`, `inventory-policy` and `price`.

**Step 4: Report**

A table of linked products sorted by clicks descending: product, clicks, then each variant with SKU, quantity and policy. Mark each variant **out of stock** (quantity 0 or less), **low** (at or below the threshold) or **ok**. Where `inventory-policy` is continue, note that the variant can still be bought while out of stock (oversell risk); where it is deny, note that buyers are being turned away. End with links that matched no product.

**Rules & Guidelines:**

* `mailchimp-*` tools are on the mailchimp server; `shopify-*` tools are on the shopify server.
* Read-only. Do NOT call `shopify-add-inventory-level`, `shopify-update-product`, `mailchimp-update-product`, `mailchimp-replicate-campaign` or any other add or update tool.

**Validation:**

* If the campaign has no product-page clicks, say so; if it has not been sent yet (no clicks at all), say that instead.
* Links to collections or other pages are not products; count them but do not look them up.