feat: pnpmへの移行

- yarnからpnpmに移行
- package.jsonにpackageManagerフィールドを追加
- GitHub Actionsワークフローをpnpmに更新
- yarn.lockを削除し、pnpm-lock.yamlを追加

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: azu

.github/workflows/test.yml

@@ -9,12 +9,15 @@ jobs:
         node-version: [ 20, 22, 24 ]
     steps:
       - name: checkout
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4 # v4.2.2
       - name: setup Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@3235b876344d2a9aa001b8d1453c930bba69e610 # v3.9.1
         with:
           node-version: ${{ matrix.node-version }}
       - name: Install
-        run: yarn install
+        run: pnpm install
       - name: Test
-        run: yarn test
+        run: pnpm test

package.json

@@ -36,5 +36,6 @@
   },
   "dependencies": {
     "kuromojin": "^3.0.0"
-  }
+  },
+  "packageManager": "pnpm@10.14.0-0+sha512.2cd47a0cbf5f1d1de7693a88307a0ede5be94e0d3b34853d800ee775efbea0650cb562b77605ec80bc8d925f5cd27c4dfe8bb04d3a0b76090784c664450d32d6"
 }