Tag overdue Rillet customers in Drip for different emails

**Objective:** Tag Drip subscribers `{tag}` (default Overdue) when their Rillet customer has an invoice at least `{days-overdue}` days past its due-date (default 1) with amount-due above zero, so Drip automations can treat them differently.

**Step 1: Find overdue customers**

Call `rillet-get-invoices` (Rillet) once. Keep invoices with amount-due above zero whose due-date is at least `{days-overdue}` days before today. Collect the distinct customer-ids with the total amount-due per currency and the oldest due-date.

**Step 2: Carry across to Drip**

Call `rillet-get-customer-emails` (Rillet) once and attach every email for each customer-id. For each email, call `drip-get-subscriber` (Drip) with email set to it. Keep emails that exist in Drip and do not already carry the tag. Skip emails with no Drip record; list them separately.

**Step 3: Confirm**

Show the user: customer name, email, amount-due, oldest due-date, and the tag to apply. Ask for explicit confirmation before writing.

**Step 4: Write**

For each confirmed email, call `drip-add-subscriber-tag` (Drip) once with email and tag set to `{tag}` (or Overdue).

**Step 5: Report**

List tagged, already tagged, not in Drip, and failed, with counts.

**Rules & Guidelines:**

* The only key shared by the two systems is the email address. Rillet emails come from `rillet-get-customer-emails` (one row per address, with its customer-id and email-type); Drip emails come from the email field of `drip-get-subscriber`. Compare them trimmed and lower-cased. Never match on name alone.
* `rillet-get-customer-emails` and `rillet-get-invoices` take no filters. Call each once, keep the result, and match in memory rather than calling them per customer.
* The only tool that may write is `drip-add-subscriber-tag` on Drip, after Step 3. Do not call `drip-add-subscriber` to create missing people, and do not call `drip-unsubscribe-subscriber`, `drip-remove-subscriber-from-all-campaigns` or `drip-start-subscriber-workflow`.
* Never call any Rillet tool whose name starts with rillet-add, rillet-update, rillet-apply, rillet-unapply, rillet-record, rillet-set or rillet-setup. Rillet is read-only in this prompt.
* This prompt does not remove the tag from customers who have since paid. Say so in the report if any tagged subscriber now has no overdue invoice.

**Validation:**

* If nothing is overdue, say so and stop.
* If the user does not confirm, stop and write nothing.