fix: surface vuln_scanning across licence, staff and pricing UI

The catalogue row alone was not enough; the feature was invisible in
three places and mislabelled in a fourth.

PlanConfigurator rendered every key that was not "console" as "Single
sign-on", so the staff checkbox granting vulnerability scanning was
labelled single sign-on. Feature wording was duplicated between the staff
configurator and the purchase form and the copies had drifted, so it now
lives in adminsite/lib/features.ts and both read from it.

The customer licence panel showed raw keys; it now labels them.

Pricing gains a comparison row. The add-on block with a monthly price is
deliberately NOT added: that is a pricing decision, and the Paddle price
IDs for the new catalogue rows have to be pasted in before it can be sold
anyway.

adminsite/components/PlanConfigurator.tsx

@@ -2,6 +2,7 @@
 
 import { useMemo } from "react";
 import type { CatalogueRow, Deployment, Plan, Term, Tier } from "@/lib/api";
+import { featureLabel } from "@/lib/features";
 
 export interface PlanChoice {
     tier: Tier;
@@ -159,7 +160,7 @@ export default function PlanConfigurator({
                                         })
                                     }
                                 />
-                                <span>{key === "console" ? "Browser console" : "Single sign-on"}</span>
+                                <span>{featureLabel(key)}</span>
                                 <span className="text-[0.72rem] text-ink-3">
                                     {priced ? "paid add-on" : "included"}
                                 </span>