Find BigCommerce orders that need follow up

**Objective:** Find orders from the last `{lookback-days}` days (default 30) that need follow-up, in channel `{channel-id}` if given.

**Step 1: Pull candidates**

Call `bigcommerce-get-order` with `date-created.from` set to the lookback start (and `channel-id` if given). Read the distinct `status` and `payment-status` values in the results before deciding what counts as a problem.

**Step 2: Flag**

Flag an order when any of these hold:

* `payment-status` is not a fully paid value (for example pending, declined or blank).
* `refunded-amount` is above zero.
* `date-shipped` is empty and `date-created` is more than 3 days old, and the status is not cancelled, refunded or completed.
* `items-shipped` is lower than `item-count` on an order marked shipped.

**Step 3: Report**

A table of flagged orders: id, customer-id, billing-email, status, payment-status, total, reason. Group by reason and put the oldest first.

**Rules & Guidelines:**

* This is a read-only job. Never call any `bigcommerce-*-add`, `bigcommerce-*-update` or `bigcommerce-*-delete` tool. Do not suggest that you changed anything.
* Never contact customers or change order statuses; list only.

**Validation:**

* If a read returns no records, say so plainly and stop; do not invent figures.
* If a result hits the maximum records limit, say the figures may be incomplete and name the filter that would narrow it.