fix(api): align alerts/commands contracts and ship full-site test suite.

Restore alert history filters and stats fields, paginate command/session logs for the SPA, show script labels on schedules, and land integration/E2E coverage with rebuilt web assets.

frontend/e2e/pages/settings.spec.mjs

@@ -0,0 +1,37 @@
+/** E2E-SET-001 / MCP-SET-001 — settings save control + success toast */
+import { test, expect } from '../fixtures.mjs'
+import { login, nav } from '../helpers.mjs'
+
+test('E2E-SET-001 settings page save control', async ({ page }) => {
+  await login(page)
+  await nav(page, '/settings')
+  await expect(page.getByText('系统设置')).toBeVisible({ timeout: 20000 })
+  await expect(page.getByRole('button', { name: '保存设置' })).toBeVisible()
+})
+
+test('E2E-SET-002 settings save success toast', async ({ page }) => {
+  await login(page)
+  await page.route(/\/api\/settings\//, async (route) => {
+    if (route.request().method() === 'PUT') {
+      await route.fulfill({
+        status: 200,
+        contentType: 'application/json',
+        body: JSON.stringify({ key: 'system_name', value: 'Nexus' }),
+      })
+      return
+    }
+    await route.continue()
+  })
+  await nav(page, '/settings')
+  await expect(page.getByLabel('系统名称')).toBeVisible({ timeout: 20000 })
+  const title = page.getByLabel('系统标题')
+  if (!(await title.inputValue()).trim()) {
+    await title.fill('Nexus Ops E2E')
+  }
+  const saveReq = page.waitForRequest(
+    (req) => req.method() === 'PUT' && req.url().includes('/api/settings/'),
+  )
+  await page.getByRole('button', { name: '保存设置' }).click()
+  await saveReq
+  await expect(page.getByText('设置已保存')).toBeVisible({ timeout: 10000 })
+})