fix(admin): use the semantic success token for the rotation-complete badge

The "safe to drop legacy key" badge hardcoded bg-emerald-600/text-white. Swap it
for the success token (border-success/bg-success/text-success) the rest of the
settings surfaces use, so it tracks the theme.

src/components/admin/encryption-section.tsx

@@ -150,7 +150,7 @@ export function EncryptionSection() {
           />
         </div>
         {s.rotationComplete ? (
-          <Badge className="bg-emerald-600 text-white hover:bg-emerald-600">
+          <Badge className="border-success/40 bg-success/15 text-success">
             {t("admin.section.encryption.safeToDropLegacy")}
           </Badge>
         ) : (