no `tsdown/client` equivalent

[EskiMojo14]

Describe the bug

Similar to vite/client, tsdown includes a tsdown/client file to register its bundler features with Typescript.

It would be useful if this was re-exported by Vite+, perhaps in vite-plus/pack/client (I see that vite/client is re-exported as vite-plus/client).

Reproduction

open-circle/schema-benchmarks#124

Steps to reproduce

replace tsdown/client in schemas/tsconfig.json with vite-plus/pack/client

System Info

admin@MacBookPro schema-benchmarks % vp env current
VITE+ - The Unified Toolchain for the Web

Environment:
  Version       24.15.0
  Source        .node-version
  Source Path   /Users/admin/schema-benchmarks/.node-version
  Project Root  /Users/admin/schema-benchmarks

Tool Paths:
  node  /Users/admin/.vite-plus/js_runtime/node/24.15.0/bin/node
  npm   /Users/admin/.vite-plus/js_runtime/node/24.15.0/bin/npm
  npx   /Users/admin/.vite-plus/js_runtime/node/24.15.0/bin/npx
admin@MacBookPro schema-benchmarks % vp --version
VITE+ - The Unified Toolchain for the Web

vp v0.1.20

Local vite-plus:
  vite-plus  v0.1.20

Tools:
  vite             v8.0.10
  rolldown         v1.0.0-rc.17
  vitest           v4.1.5
  oxfmt            v0.46.0
  oxlint           v1.61.0
  oxlint-tsgolint  v0.22.0
  tsdown           v0.21.10

Environment:
  Package manager  pnpm v10.33.2
  Node.js          v24.15.0 (.node-version)

Used Package Manager

pnpm

Logs

Validations

• Read the Contributing Guidelines.
• Check that there isn't already an issue for the same bug.
• Confirm this is a Vite+ issue and not an upstream issue (Vite, Vitest, tsdown, Rolldown, or Oxc).
• The provided reproduction is a minimal reproducible example.