Add or remove named contacts on a HubSpot list

**Objective:** `{operation}` (add or remove; default add) the contacts `{contact-emails}` on the manual list `{list-name}`.

**Step 1: Resolve the list**

Call `hubspot-get-lists` with `name.contains` = `{list-name}`. If none or several match, list them and stop. If its `processing-type` is not MANUAL, say HubSpot manages its members and stop.

**Step 2: Resolve the contacts**

For each address in `{contact-emails}` (comma-separated), call `hubspot-get-contacts` with `email` = it. Collect the record-ids. List any address that matched no contact.

**Step 3: Check current membership**

For each contact call `hubspot-get-contact-list-membership` with `contact-id` = its record-id and `list-id` = the list's ID. For add, drop contacts already on the list; for remove, drop contacts not on it. Say which were dropped.

**Step 4: Confirm**

Show the list name and ID, the operation, and the contacts it will change (name, email, record-id). Wait for an explicit yes.

**Step 5: Write**

* add: `hubspot-add-list-members` once with `list-id` and `record-ids` = the remaining record-ids, comma-separated
* remove: `hubspot-remove-list-members` once with the same

**Step 6: Report**

Report what changed and which addresses were skipped and why.

**Rules & Guidelines:**

* Only the one tool in Step 5 may write, once, after Step 4.
* Do NOT call any other write tool: no other hubspot-add, hubspot-update, hubspot-rename, hubspot-remove, hubspot-subscribe, hubspot-unsubscribe or hubspot-import tool.

**Validation:**

* If `{operation}` is not add or remove, ask which and stop.
* If no contacts remain after Step 3, say nothing needs to change and stop.