Build a Mailchimp tag of overdue Sage Intacct customers

**Objective:** Find Intacct customers with invoices more than `{days-overdue}` days past due (default 30) and add their existing contacts in the Mailchimp audience `{audience}` to the static segment or tag `{segment}`, so marketing can exclude or target them. Nothing is written until the user confirms.

**Step 1: Resolve the audience and segment in Mailchimp**

Call `mailchimp-get-list` filtered by `name` = `{audience}` and take its `list-id`. If none or more than one match, list what was found and stop.

Call `mailchimp-get-segment` filtered by `list-id` and `name` = `{segment}`. Take its `segment-id` and `type`. If no segment matches, stop and tell the user to create the tag in Mailchimp first; this prompt cannot create one. If the segment is not static (a saved segment is driven by conditions), stop and explain that members cannot be added to it.

**Step 2: Find overdue customers in Intacct**

Call `intacct-get-invoice` with `total-due.min` = 0.01 and `due-date.to` = today minus the days overdue. Group by `customer-id` and total `total-due`. For each customer, call `intacct-get-customer` filtered by `customer-id` for `customer-name` and `email`, and `intacct-get-contact` filtered by `company-name` = the customer-name for contact emails. Remove duplicate addresses.

**Step 3: Work out who to tag**

For each address:

1. Call `mailchimp-get-list-member` filtered by `email` and `list-name` = `{audience}`. If the address is not a member of the audience, do not add it; list it under "not in audience".
2. Call `mailchimp-get-segment-member` filtered by `segment-id` and `email`. If it is already in the segment, list it under "already tagged".

Everything left is the plan.

**Step 4: Confirm**

Show the plan as a table: customer-name, overdue total, email, member status. Show the "not in audience" and "already tagged" lists below it. Ask the user to confirm. Do not continue without an explicit yes. If the plan is empty, say so and stop.

**Step 5: Tag**

For each confirmed address, call `mailchimp-add-segment-member` with `segment-id`, `list-id` and `email-address`. Then call `mailchimp-get-segment-member` filtered by `segment-id` and `email` to confirm it landed. Report each address as tagged or failed, with the error for failures.

**Rules & Guidelines:**

* `mailchimp-get-list`, `mailchimp-get-segment`, `mailchimp-get-list-member`, `mailchimp-get-segment-member` and `mailchimp-add-segment-member` are on the mailchimp server. `intacct-get-invoice`, `intacct-get-customer` and `intacct-get-contact` are on the intacct server.
* Match email addresses case-insensitively and after trimming spaces. If an Intacct email field holds several addresses separated by commas or semicolons, treat each one as a separate address.
* Intacct `intacct-get-customer` has no email filter. To go from an email to an Intacct customer, call `intacct-get-contact` filtered by `email`, take its `company-name`, then call `intacct-get-customer` filtered by `customer-name` with that value.
* The only write allowed is `mailchimp-add-segment-member`, and only after confirmation. Do NOT call `mailchimp-add-list-member` (never add someone to the audience), `mailchimp-update-list-member`, or any create or update tool on the intacct server.

**Validation:**

* Tagging a member whose status is unsubscribed or cleaned is allowed (tags do not send email), but mark them in the plan.
* If a tag call fails, keep going with the rest and report the failures at the end.