External links cannot jump correctly when the base attribute is enabled

[ajiho]

Describe the bug

This is the sidebar configuration

themeConfig: {
sidebar:{
  "/en/": {
    "base": "/en/",
    "items": [
      {
        "text": "introduce",
        "items": [
          {
            "text": "Release log",
            "link": "releases"
          },
          {
            "text": "Upgrade",
            "link": "upgrade"
          },
          {
            "text": "foo",
            "link": "https://foo.com/"
          }
        ]
      }
    ]
  }
}
}

When I make some changes, it returns to normal

themeConfig: {
sidebar:{
  "/en/": {
    "items": [
      {
        "text": "introduce",
        "items": [
          {
            "text": "Release log",
            "link": "/en/releases"
          },
          {
            "text": "Upgrade",
            "link": "/en/upgrade"
          },
          {
            "text": "foo",
            "link": "https://foo.com/"
          }
        ]
      }
    ]
  }
}
}

Reproduction

unnecessary

Expected behavior

When I enable the base attribute, it allows external links in the submenu to be accessed normally

System Info

System:
    OS: Windows 10 10.0.19044
    CPU: (8) x64 Intel(R) Core(TM) i7-4720HQ CPU @ 2.60GHz
    Memory: 1.34 GB / 7.91 GB
  Binaries:
    Node: 22.11.0 - C:\Program Files\nodejs\node.EXE      
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Internet Explorer: 11.0.19041.3636
  npmPackages:
    vitepress: ^1.5.0 => 1.5.0

### Additional context

_No response_

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