Update Constant Contact contacts, changing only what you asked

**Objective:** Update the contact with the email address `{email-address}` with these changes: `{changes}`.

**Step 1: Find the contact**

Call `constant-contact-get-contact` with `email-address` set to `{email-address}`. If nothing comes back, say no contact has that address and stop. Keep the contact-id.

**Step 2: Work out the change**

Map `{changes}` onto the fields `constant-contact-update-contact` accepts: first-name, last-name, email, phone, job-title, company-name, permission-to-send. If a requested change is not one of these (an address, a tag, a list), say these tools cannot change it and leave it out.

* A new email: first call `constant-contact-get-contact` with the new address. If another contact already has it, stop and report the clash.
* Phone: the update replaces all of the contact's phone numbers; say so.
* permission-to-send: if the contact is currently unsubscribed, refuse to change it. Only set explicit when the user states the contact opted in.

**Step 3: Confirm**

Show a table of each changing field: current value, new value. Ask the user to confirm. Do not proceed without an explicit yes.

**Step 4: Update**

Call `constant-contact-update-contact` exactly once with the contact-id and only the changed fields. Then call `constant-contact-get-contact` with the contact-id and show the stored values to confirm.

**Rules & Guidelines:**

* `constant-contact-update-contact` is the only write tool this prompt may call. Do not call `constant-contact-add-contact` or `constant-contact-add-contact-note`.
* Leave fields the user did not mention out of the call, so they keep their values.

**Validation:**

* If `{changes}` is unclear, ask what should change and stop.