package.json has no packageManager field — pnpm lockfile churns across pnpm versions

[RUKAYAT-CODER]

CI pins pnpm 11 (pnpm/action-setup with version: 11) but package.json has no packageManager field. A local pnpm 10 run rewrites pnpm-lock.yaml in a very different format (a ~9,500-line diff was observed), and pnpm install --no-frozen-lockfile in CI means the lockfile can drift silently.

Fix: add "packageManager": "pnpm@11.x.x" to package.json (corepack will then use it) and consider --frozen-lockfile in CI installs.

[Meet-hybrid]

I would like to contribute to this issue. I have experience with JavaScript/TypeScript, React, backend APIs, testing, Git, and software architecture. I will follow the acceptance criteria, add tests, and provide a focused pull request.