feat(23-02): add acknowledge_user manual action case to ActionAreaCard

- Add acknowledge_user: 'Acknowledge user' to ACTION_LABEL
- Add case 'acknowledge_user' to ActionParamsForm mirroring no_action (no-params form)
- Renders as a normal checkbox + Approve action for every company; no automation-gate logic added (D-04) — the auto-approval carve-out lives only in the webhook path (Plan 05)

components/phishing/action-area-card.tsx

@@ -72,6 +72,7 @@ const ACTION_LABEL: Record<string, string> = {
   reset_password: 'Reset password',
   isolate_endpoint: 'Isolate endpoint',
   disable_forwarding_rule: 'Disable forwarding rule',
+  acknowledge_user: 'Acknowledge user',
 };
 
 function humanizeAction(actionType: string): string {
@@ -130,6 +131,12 @@ function ActionParamsForm({
           No parameters — informational verdict, no remediation needed.
         </p>
       );
+    case 'acknowledge_user':
+      return (
+        <p className="text-sm text-muted-foreground">
+          No parameters — posts a customer-visible thank-you note to the reporting employee.
+        </p>
+      );
     case 'warn_user':
       return (
         <div className="grid gap-3 sm:grid-cols-2">