Add the detection for the GOV.UK Design System UI library

src/apps.json

@@ -14178,6 +14178,18 @@
       "icon": "pagefly.png",
       "script": "pagefly\\.io",
       "website": "https://pagefly.io"
+    },
+    "GOV.UK Frontend": {
+      "cats": [
+        66,
+        19
+      ],
+      "html": [
+        "<body[^>]+govuk-template__body",
+        "<a[^>]+govuk-link"
+      ],
+      "icon": "govuk.png",
+      "website": "https://design-system.service.gov.uk/"
     }
   },
   "categories": {
@@ -14438,4 +14450,4 @@
       "priority": 7
     }
   }
-}
+}