feat(widget): 准备 npm 包发布

- 添加 GitHub Actions 工作流以在推送标签时自动发布到 npm
- 更新 package.json，包含包名、版本、描述、作者等信息
- 添加 README.md、LICENSE 和 .npmignore 文件
- 更新根目录 .gitignore，忽略 .npmrc 文件

.github/workflows/npm_publish.yml

@@ -0,0 +1,37 @@
+name: Publish widget to npm
+
+on:
+  push:
+    tags:
+      - "widget-v*"
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+
+      - name: Use Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+          registry-url: "https://registry.npmjs.org"
+
+      - name: Install dependencies
+        working-directory: docs/widget
+        run: npm ci
+
+      - name: Build widget
+        working-directory: docs/widget
+        run: npm run build
+
+      - name: Publish to npm
+        working-directory: docs/widget
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: npm publish --access public