feat: support project-aware global shims for vp-installed global CLIs

## Summary
Add support in vite-plus for project-aware global shims for CLIs installed via `vp i -g`.

## pnpm reference
pnpm documents project-aware global bins here:
https://pnpm.io/global-packages#project-aware-global-bins

From the docs, the relevant behavior is:
- globally installed packages are isolated from each other
- bin shims are generated in the global bin directory
- those shims point into the appropriate install group
- the invoked CLI can operate with awareness of the current project context

## What we want for vite-plus
For CLIs installed via `vp i -g`:
- global shims should be available as normal executables
- when invoked inside a project, the shim/runtime should resolve against the current project context where appropriate
- the behavior should feel similar to local project bins, but for globally installed tooling

## Open questions
- Should vite-plus mirror pnpm's approach closely, or adapt it to vp's own installation/runtime model?
- What project context needs to be discovered at execution time?
- Are there edge cases around resolution, workspace roots, or cross-platform shim generation?

Commencez par la référence des bins globaux tenant compte du projet de pnpm et retracez la manière dont `vp i -g` installe actuellement les CLIs globales. Définissez le contexte du projet, le comportement de résolution, la gestion de la racine du workspace et les attentes concernant les shims multiplateformes avant d’identifier les points d’implémentation. Le travail est considéré comme terminé lorsque les CLIs installées globalement se comportent comme des exécutables normaux tout en résolvant correctement le contexte du projet.

Rédigé par le modèle d'indexation à partir du texte de l'issue.