Fix DNS2 self-updater path and sync live dashboard version UI

dashcaddy-api/__tests__/routes/health.routes.test.js

@@ -524,9 +524,7 @@ describe('Health Routes', () => {
     it('returns error when no url parameter provided', async () => {
       const { app } = createApp();
       const res = await request(app).get('/api/health/probe');
-      // ValidationError is not imported at module scope, so this throws a ReferenceError
-      // which the error handler catches as a 500
-      expect(res.status).toBe(500);
+      expect(res.status).toBe(400);
     });
   });