Send payment reminders only to customers who owe money

**Objective:** Add every subscribed Mailchimp contact whose Dynamics SL customer has a current balance of at least `{min-balance}` (default 0.01) to the static segment or tag `{segment}` in audience `{audience}`.

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

Call `mailchimp-get-list` with `name` set to `{audience}` and keep its list-id. Call `mailchimp-get-segment` with `list-id` and `name` set to `{segment}`. If the segment does not exist, stop and tell the user to create the tag in Mailchimp first; this prompt does not create segments. If its type is saved (condition-based) rather than static, stop: members cannot be added to a saved segment.

**Step 2: Read balances in Dynamics SL**

Call `dynamics-sl-get-customer-balances` with `current-balance.min` set to `{min-balance}` and `max-records` set to 500. For each customer-id, call `dynamics-sl-get-customers` with `customer-id` to get email-address.

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

For each email, call `mailchimp-get-list-member` with `email` and `list-name` set to the audience name. Keep only contacts whose status in this audience is subscribed. Then call `mailchimp-get-segment-member` with `segment-id` and `list-id` and drop anyone already in the segment.

**Step 4: Confirm before writing**

Show the contacts to add (customer-name, email, current-balance) and the counts skipped as already tagged, not subscribed, not in the audience, or no email. Ask the user to confirm. Do not write until they do.

**Step 5: Add and confirm**

For each confirmed contact, call `mailchimp-add-segment-member` once with `segment-id`, `list-id` and `email-address`. Then call `mailchimp-get-segment-member` with the segment-id and report added, failed (with the error) and skipped counts.

**Rules & Guidelines:**

* Tools whose names start with mailchimp- are on the mailchimp server; tools whose names start with dynamics-sl- are on the dynamics-sl server. If either set is missing from your tool list, stop and say which server is not connected.
* The only write tool this prompt may call is `mailchimp-add-segment-member`, after Step 4. Do not call `mailchimp-add-list-member`, `mailchimp-update-list-member`, `mailchimp-start-automation` or any other mailchimp write tool. Adding to the segment must not subscribe anyone.
* This prompt does not remove contacts whose balance has since been paid; say so in the report and list segment members with no Dynamics SL balance so the user can untag them in Mailchimp.
* Match email addresses case-insensitively after trimming spaces.
* Pass `company` on the dynamics-sl tools only if the user named a company.

**Validation:**

* If `{min-balance}` is empty or not a number, use 0.01.
* If there is nobody to add, report the skipped counts and stop without writing.