fix: 修复公众号消息读取与 Windows 中文路径兼容

- 支持从 biz_message 分片读取公众号聊天记录
- 在左侧栏增加独立的公众号折叠分组
- 为 Windows 中文数据目录建立 ASCII 路径桥接 (#12)
- 补充公众号分片、侧栏分类和路径桥接测试

tests/component/conversation-sidebar.test.tsx

@@ -0,0 +1,57 @@
+import { render, screen } from '@testing-library/react'
+import userEvent from '@testing-library/user-event'
+import { describe, expect, it, vi } from 'vitest'
+import { ConversationSidebar } from '../../src/renderer/src/components/conversation/ConversationSidebar'
+
+vi.mock('@tanstack/react-virtual', () => ({
+  useVirtualizer: ({ count }: { count: number }) => ({
+    getTotalSize: () => count * 58,
+    getVirtualItems: () =>
+      Array.from({ length: count }, (_, index) => ({
+        index,
+        key: index,
+        start: index * 58,
+        size: 58
+      }))
+  })
+}))
+
+describe('ConversationSidebar', () => {
+  it('keeps official accounts in their own collapsible section', async () => {
+    render(
+      <ConversationSidebar
+        contacts={[
+          {
+            m_nsUsrName: 'gh_fixture',
+            m_nsNickName: '测试公众号',
+            md5: 'official-md5',
+            type: 'user',
+            isOfficialAccount: true
+          },
+          {
+            m_nsUsrName: 'wxid_fixture',
+            m_nsNickName: '测试联系人',
+            md5: 'contact-md5',
+            type: 'user'
+          }
+        ]}
+        selectedContact={null}
+        onSelectContact={vi.fn()}
+        onSearch={vi.fn()}
+        onContentFilter={vi.fn()}
+        width={320}
+        selfInfo={null}
+        dbReady
+        onOpenSettings={vi.fn()}
+        onRefresh={vi.fn(async () => undefined)}
+      />
+    )
+
+    expect(screen.getByRole('button', { name: '公众号 (1)' })).toBeInTheDocument()
+    expect(screen.getByRole('button', { name: '联系人 (1)' })).toBeInTheDocument()
+    expect(screen.queryByText('测试公众号')).not.toBeInTheDocument()
+
+    await userEvent.click(screen.getByRole('button', { name: '公众号 (1)' }))
+    expect(screen.getByText('测试公众号')).toBeInTheDocument()
+  })
+})