Add overflow menu to system tabs on mobile (#24543)

* add overflow menu to system tabs on mobile

* add default icon, observe measure div, fix tests

web/e2e/helpers/system-tabs.ts

@@ -0,0 +1,11 @@
+import type { FrigateApp } from "../fixtures/frigate-test";
+
+// On mobile the System tabs sit in an OverflowStrip, which keeps an inert copy
+// of every tab for measurement and hides the ones that do not fit behind a
+// kebab. The selected tab always stays in the strip.
+
+export function systemTab(frigateApp: FrigateApp, name: string) {
+  return frigateApp.page
+    .locator(`[aria-label="Select ${name}" i]:not([inert] *)`)
+    .first();
+}