chore: update GitHub Actions to latest major versions

- actions/checkout v4 → v6
- actions/setup-node v4 → v6
- cycjimmy/semantic-release-action v4 → v6 (pinned semantic_version: 24)
- github/codeql-action v3 → v4
- actions/stale v9 (already latest)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/build.yml

@@ -18,9 +18,9 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Setup Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
       - name: Install dependencies