[Bug] npx install fails with ETARGET: missing documentpreview@0.1.5-rc.3

[youziyyds123]

Clean install fails with:

```text
npm error code ETARGET
npm error notarget No matching version found for @deepseek-ai/dsh-client-ui-sidebar-documentpreview@^0.1.5-rc.3.

Environment:

Windows 11
Node v24.18.0
npm 11.16.0
registry: https://registry.npmjs.org/

Reproduce:

npx @deepseek-ai/dsh web

Dependency chain:

@deepseek-ai/dsh@0.1.5-rc.2
→ @deepseek-ai/dsh-web-app@0.1.5-rc.3
→ @deepseek-ai/dsh-client-ui-sidebar-documentpreview@^0.1.5-rc.3
→ ETARGET

I reproduced this after deleting .dsh, clearing the npx cache, and confirming there was no global DSH installation.