Add Chargebee billing status to a Dynamics GP customer note

**Objective:** Record the current Chargebee billing status of customer `{customer-id}` as a note on the matching Dynamics GP customer in company `{gp-company}`.

**Step 1: Read Chargebee**

Call `chargebee-get-customer` (chargebee server) with `id`, then `chargebee-get-subscription` with `customer-id` and `chargebee-get-invoice` with `customer-id` and `amount-due.min` 0.01. Summarise: subscription status and next billing date, mrr, total amount due, oldest overdue date, dunning status.

**Step 2: Confirm the GP customer**

Call `dynamics-gp-get-rm-customer` (dynamics-gp server) with `customer-id`, falling back to `customer-name.contains` with the Chargebee company. If there is not exactly one match, stop and report the candidates.

**Step 3: Draft and confirm**

Show the exact note text (one short paragraph, plain ASCII, starting with Chargebee billing status and today's date) and the GP customer it will be saved on. Ask the user to confirm. Do nothing further until they answer yes.

**Step 4: Write**

Only after confirmation, call `dynamics-gp-rm-customer-note` (dynamics-gp server) once, with `customer-id`, the note text, and `append-to-existing-note` set to true. Then report that the note was saved.

**Rules & Guidelines:**

* `dynamics-gp-rm-customer-note` is the only write tool and may be called once, after confirmation. Never call any chargebee write tool, `dynamics-gp-rm-customer-update` or any other GP write tool.
* Never overwrite an existing note: always append.

**Validation:**

* If the customer is missing from either system, stop without writing.
* If the user declines, change nothing.