ci: release.yml 재작성 + publish.yml 추가

release.yml: Node 매트릭스 제거, Node 20.x 단일, actions v3→v4 업그레이드.
deprecated upload-release-asset@v1 → softprops/action-gh-release@v2.
단일 패키지 npm ci && npm run build 로 통합.
publish.yml: workflow_dispatch 수동 트리거 npm publish 추가.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.github/workflows/publish.yml

@@ -0,0 +1,25 @@
+name: Publish to npm
+
+on:
+  workflow_dispatch:
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20.x'
+          registry-url: 'https://registry.npmjs.org'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Publish
+        run: npm publish --access public
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}