chore(repo): switch package manager references from pnpm to utoo

[killagu]

Summary

• Replace pnpm with utoo across docs, top-level scripts, and CI workflows so the repo guidance matches the package manager the project actually uses.
• Update packageManager in package.json to utoo@1.0.28; switch scripts/{publish,version,utils}.js to invoke utoo (and align their comments).
• In .github/workflows/release.yml and .github/workflows/e2e-test.yml, swap pnpm/action-setup for utooland/setup-utoo and call ut / utoo (mirroring the pattern already used by ci.yml).
• Preserve filenames (pnpm-lock.yaml, pnpm-workspace.yaml) and the CLI argument value in ut install --from pnpm — those reference real artifacts on disk and a flag value, not tool invocations.
• Out of scope (intentionally untouched): historical CHANGELOG.md entries, source code that detects pnpm node_modules layouts (packages/core/src/loader/*), and the plugin-pnpm* test fixtures.

Test plan

• CI green on next for typecheck, build, lint, format check, and tests.
• release.yml (workflow_dispatch dry-run) completes through install + build using ut install --from pnpm and ut run build.
• e2e-test.yml succeeds end-to-end; in particular confirm PUBLINT_PACK: utoo is accepted by publint — if not, revert that env var to npm and keep the rest.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores

  • Switched project package manager metadata and CI/release/publish workflows from pnpm to utoo.
  • Added a packaging CLI to produce package tarballs and adjusted publish/version tooling to use utoo.
  • Bumped required Node.js minimum to >= 22.18.0.

• Documentation

  • Updated README, guides, quickstarts and contributor docs to use utoo install/run/build/test commands.