ci: fix pnpm action-setup version source

[ayden94]

Problem

CI keeps failing on every push to main with:

Error: No pnpm version is specified.
Please specify it by one of the following ways:
  - in the GitHub Action config with the key "version"
  - in the package.json with the key "packageManager"

pnpm/action-setup@v4 requires a pnpm version via either the version input or the packageManager field. .github/workflows/ci.yml does not pass version, and package.json does not declare packageManager, so the action has no source for the version and aborts at the Set up pnpm step.

This is the same root cause that left PR #5 (and earlier docs syncs) red on main — Sync Docs passes because it does not use pnpm, but CI and Release both fail before any project step runs.

Fix

Add packageManager: pnpm@10.17.1 to package.json. This is the corepack standard source of truth and matches the version that produced the committed pnpm-lock.yaml (lockfileVersion 9.0).

Verification

• pnpm install → ok, lockfile unchanged
• pnpm run typecheck → ok
• pnpm test → ok (where applicable)

Notes

• No changeset: dev-only metadata, no published-package surface impact.
• Bun version is intentionally not pinned here — oven-sh/setup-bun@v1 defaults to a recent stable release and is outside the scope of this fix.
• Same fix already merged for ilokesto/state in PR perf: setState fast path — middleware 없을 때 체인 구성 스킵 + runner 캐싱 #6.