Add frontend tests (#22783)

* basic e2e frontend test framework

* improve mock data generation and add test cases

* more cases

* add e2e tests to PR template

* don't generate mock data in PR CI

* satisfy codeql check

* fix flaky system page tab tests by guarding against crashes from incomplete mock stats

* reduce local test runs to 4 workers to match CI

web/e2e/specs/settings/ui-settings.spec.ts

@@ -0,0 +1,40 @@
+/**
+ * Settings page tests -- HIGH tier.
+ *
+ * Tests settings page rendering with content, form controls,
+ * and section navigation.
+ */
+
+import { test, expect } from "../../fixtures/frigate-test";
+
+test.describe("Settings Page @high", () => {
+  test("settings page renders with content", async ({ frigateApp }) => {
+    await frigateApp.goto("/settings");
+    await frigateApp.page.waitForTimeout(2000);
+    await expect(frigateApp.page.locator("#pageRoot")).toBeVisible();
+    const text = await frigateApp.page.textContent("#pageRoot");
+    expect(text?.length).toBeGreaterThan(0);
+  });
+
+  test("settings page has clickable navigation items", async ({
+    frigateApp,
+  }) => {
+    await frigateApp.goto("/settings");
+    await frigateApp.page.waitForTimeout(2000);
+    const navItems = frigateApp.page.locator(
+      "#pageRoot button, #pageRoot [role='button'], #pageRoot a",
+    );
+    const count = await navItems.count();
+    expect(count).toBeGreaterThan(0);
+  });
+
+  test("settings page has form controls", async ({ frigateApp }) => {
+    await frigateApp.goto("/settings");
+    await frigateApp.page.waitForTimeout(2000);
+    const formElements = frigateApp.page.locator(
+      '#pageRoot input, #pageRoot button[role="switch"], #pageRoot button[role="combobox"]',
+    );
+    const count = await formElements.count();
+    expect(count).toBeGreaterThanOrEqual(0);
+  });
+});