Separate real prospects from existing Rillet customers

**Objective:** List active Drip subscribers with a lead score of at least `{min-lead-score}` (default 50) whose email address does not belong to any Rillet customer.

**Step 1: Read engaged subscribers**

Call `drip-get-subscriber` (Drip) with status set to active and lead-score.min set to `{min-lead-score}` (or 50 if blank).

**Step 2: Read Rillet customer emails**

Call `rillet-get-customer-emails` (Rillet) once and build a set of lower-cased emails.

**Step 3: Compare**

Keep subscribers whose email is not in that set. As a secondary hint only, note when the subscriber's email domain matches the domain of a Rillet customer email, since they may belong to an existing customer under another address.

**Step 4: Report**

A table sorted by lead-score, highest first: email, first and last name, lead-score, lifetime-value, tags, created-date, and "possible existing customer" with the matched customer name where the domain matched.

**Rules & Guidelines:**

* The only key shared by the two systems is the email address. Rillet emails come from `rillet-get-customer-emails` (one row per address, with its customer-id and email-type); Drip emails come from the email field of `drip-get-subscriber`. Compare them trimmed and lower-cased. Never match on name alone.
* This prompt is read-only. Do not call `drip-add-subscriber`, `drip-update-subscriber`, `drip-add-subscriber-tag`, `drip-remove-subscriber-tag`, `drip-add-subscriber-to-campaign`, `drip-remove-subscriber-from-campaign`, `drip-remove-subscriber-from-all-campaigns`, `drip-unsubscribe-subscriber`, `drip-start-subscriber-workflow`, `drip-remove-subscriber-from-workflow`, `drip-activate-campaign`, `drip-pause-campaign`, `drip-activate-workflow`, `drip-pause-workflow` on Drip, and do not call any Rillet tool whose name starts with rillet-add, rillet-update, rillet-apply, rillet-unapply, rillet-record, rillet-set or rillet-setup.
* Ignore free-mail domains (gmail.com, outlook.com, yahoo.com, hotmail.com, icloud.com) for the domain hint.

**Validation:**

* If Drip returns no subscribers at that score, say so and suggest a lower `{min-lead-score}`.
* If every engaged subscriber is already a customer, say so in one line.