navbar has problems with activematch

[BlazeSnow]

Describe the bug

无论在Examples的activematch输入任何内容，test被高亮时，Examples总是会高亮。

Whenever you enter anything in the Examples' activematch, the Examples will always be highlighted when test is highlighted.

      {
        text: 'Examples',
        activeMatch: '/whatever/',
        items: [
          {
            text: 'test',
            activeMatch: '/test/',
            link: '/test/',
          },
          {
            text: 'another',
            activeMatch: '/another/',
            link: '/another/',
          }
        ]
      },

Reproduction

https://blazesnow-vitepressissue.vercel.app/

https://github.com/BlazeSnow/VitepressIssue

Expected behavior

最上一级的activematch应当匹配组内的activematch，而不是输入任何值都可以使最上一级的activematch高亮。

The uppermost level of activematch should match the activematch in the group, rather than entering any value that will make the uppermost level of activematch highlighted.

System Info

System:
    OS: Windows 11 10.0.26100
    CPU: (20) x64 12th Gen Intel(R) Core(TM) i7-12700H
    Memory: 6.28 GB / 15.69 GB
  Binaries:
    Node: 23.1.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Chromium (129.0.2792.65)
    Internet Explorer: 11.0.26100.1882
  npmPackages:
    vitepress: ^1.4.2 => 1.4.3

Additional context

No response

Validations

• Check if you're on the latest VitePress version.
• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.