Rename extension references to Chromium

Updated all documentation, configuration, and code references from 'Xget for Chrome' to 'Xget for Chromium' for consistency with supported browsers. This includes issue templates, workflow files, privacy and security policies, source code logs, manifest, and popup UI.

.github/workflows/publish-extension.yml

@@ -172,7 +172,7 @@ jobs:
         uses: softprops/action-gh-release@v2
         with:
           tag_name: v${{ steps.version.outputs.version }}
-          name: Xget for Chrome ${{ steps.version.outputs.version }}
+          name: Xget for Chromium ${{ steps.version.outputs.version }}
           files: |
             chrome-extension.zip
             edge-extension.zip
@@ -221,7 +221,7 @@ jobs:
 
       - name: 通知成功
         run: |
-          echo "🎉 成功发布 Xget for Chrome ${{ steps.version.outputs.version }} 到多个商店！"
+          echo "🎉 成功发布 Xget for Chromium ${{ steps.version.outputs.version }} 到多个商店！"
           echo "🔗 Chrome 网上应用店: https://chrome.google.com/webstore/detail/${{ secrets.CHROME_EXTENSION_ID }}"
           echo "🔗 Microsoft Edge 加载项: 查看发布页面获取手动安装文件"
           echo "📦 GitHub 发布: https://github.com/${{ github.repository }}/releases/tag/v${{ steps.version.outputs.version }}"