Update Constant Contact when a customer changes in Dynamics SL

**Objective:** Bring the Constant Contact contact for Dynamics SL customer `{customer}` in line with the SL record, treating Dynamics SL as the source of truth for company name and phone number. Nothing changes until the user confirms.

**Step 1: The customer in Dynamics SL**

Call `dynamics-sl-get-customers` with `customer-id` = `{customer}`; if nothing comes back, use `customer-name.contains` = `{customer}`. If more than one matches, list them and stop.

**Step 2: The contact in Constant Contact**

Call `constant-contact-get-contact` with the customer's `email-address` as `email-address`. If no contact matches, say so, suggest the add-missing-customers-to-constant-contact prompt, and stop. If more than one matches, list them and stop.

**Step 3: Compare**

Compare SL `customer-name` with contact `company-name`, and SL `phone-number` with contact `phone-number`, ignoring case, spacing and phone punctuation. Show a table of field, Constant Contact value and Dynamics SL value for each field that differs. If none differ, say the records agree and stop.

**Step 4: Confirm**

Ask the user to confirm the changes. Do not update anything until they reply yes.

**Step 5: Update and confirm**

Call `constant-contact-update-contact` once with the `contact-id` and only the fields that differ (`company-name`, `phone`). Leave every other property out so it keeps its value. Then call `constant-contact-get-contact` again and report the before and after values.

**Rules & Guidelines:**

* `dynamics-sl-get-customers` is on the dynamics-sl server and is only read; nothing is ever written back to Dynamics SL.
* The only write tool this prompt may call is `constant-contact-update-contact`, once, after confirmation. Never change `email` or `permission-to-send` here.
* If the user has named a Dynamics SL company, pass it as `company` on every dynamics-sl call.

**Validation:**

* If the SL value is blank, do not overwrite a non-blank Constant Contact value with it.
* If the update fails, report the error and do not retry.