fix: add missing picomatch dev dependency

[0xFANGO]

Summary

• vite-plus-core@0.1.18 requires picomatch at runtime but doesn't declare it in its own package.json
• Under pnpm's strict node_modules isolation, this causes MODULE_NOT_FOUND on pnpm run build
• Added picomatch as a dev dependency to work around the upstream omission

Test plan

• pnpm run build succeeds

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Note

Low Risk
Low risk: dependency-only change to resolve a build-time MODULE_NOT_FOUND under pnpm; no runtime/business logic code changes.

Overview
Fixes pnpm builds by explicitly adding picomatch@^4.0.4 as a dev dependency (and updating pnpm-lock.yaml) to satisfy an undeclared runtime requirement from vite-plus/vite-plus-core.

^{Reviewed by Cursor Bugbot for commit 9db1213. Configure here.}