Update GitHub Actions to latest versions

- Update actions/checkout@v2/v3 → @v4
- Update actions/configure-pages@v1 → @v5
- Update actions/deploy-pages@v3 → @v4
- Fix deprecated action versions warnings

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

Co-Authored-By: Claude <[email protected]>

Author: kurehajime

.github/workflows/firebase-hosting-merge.yml

@@ -10,7 +10,7 @@ jobs:
   build_and_deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: npm ci && npm run build
       - uses: FirebaseExtended/action-hosting-deploy@v0
         with:

.github/workflows/firebase-hosting-pull-request.yml

@@ -8,7 +8,7 @@ jobs:
     if: '${{ github.event.pull_request.head.repo.full_name == github.repository }}'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: npm ci && npm run build
       - uses: FirebaseExtended/action-hosting-deploy@v0
         with:

.github/workflows/pages.yml

@@ -33,9 +33,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Pages
-        uses: actions/configure-pages@v1
+        uses: actions/configure-pages@v5
       - name: Setup Node
         uses: actions/setup-node@v4
         with:
@@ -49,4 +49,4 @@ jobs:
           path: './docs'
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v3
+        uses: actions/deploy-pages@v4