fix: prevent page overflow from hidden tooltips (#15156)

app/javascript/entrypoints/dashboard.js

@@ -88,6 +88,15 @@ app.use(FloatingVue, {
   instantMove: true,
   arrowOverflow: false,
   disposeTimeout: 5000000,
+  // Use the `fixed` strategy so tooltips are positioned relative to the viewport.
+  // With the default `absolute` strategy, a hidden tooltip lingers at a stale offset
+  // and adds to the page's scroll height, letting the whole dashboard over-scroll.
+  // Fixed elements never affect scroll height, so this can't happen.
+  themes: {
+    tooltip: {
+      strategy: 'fixed',
+    },
+  },
 });
 app.use(hljsVuePlugin);