test: 建立桌面端自动化回归测试体系并完善跨平台 CI

(cherry picked from commit 74267ae2f63f8256c3da84b04f5b330e6e9d4c67)

tests/component/empty-state.test.tsx

@@ -0,0 +1,18 @@
+import { render, screen } from '@testing-library/react'
+import { describe, expect, it } from 'vitest'
+import { EmptyConversationState } from '../../src/renderer/src/components/chat/EmptyConversationState'
+import { SettingsEmptyState } from '../../src/renderer/src/features/settings/components/SettingsEmptyState'
+
+describe('empty states', () => {
+  it('explains how to leave an empty archive without pretending data failed', () => {
+    render(<EmptyConversationState />)
+    expect(screen.getByRole('heading', { name: '选择一条消息' })).toBeVisible()
+    expect(screen.getByText('从左侧选择群聊或联系人以浏览历史记录')).toBeVisible()
+  })
+
+  it('labels an unavailable settings section explicitly', () => {
+    render(<SettingsEmptyState label="测试设置" />)
+    expect(screen.getByRole('heading', { name: '测试设置' })).toBeVisible()
+    expect(screen.getByText('该设置将在后续阶段接入。')).toBeVisible()
+  })
+})