Method fetchFavicon

src/main/api/renderer/webSearch.ts:288–317

* 获取网站 favicon * 解析目标网站 HTML，提取 标签获取 favicon URL， * 然后下载图标并转为 base64

(url: string)

   * 然后下载图标并转为 base64
   */
  public async fetchFavicon(url: string): Promise<string> {
    try {
      const candidateUrl = this.ensureUrlProtocol(url.replace('{q}', 'test').trim())
      const urlObj = new URL(candidateUrl)
      const origin = urlObj.origin

      // 先尝试请求网页获取 favicon link。部分站点的压缩响应会导致 Electron net
      // 解码失败，这里只跳过 HTML 解析，仍继续回退到 /favicon.ico。
      try {
        const html = await this.httpGet(`${origin}/`)
        const faviconUrl = this.parseFaviconFromHtml(html, origin)

        if (faviconUrl) {
          const base64 = await this.downloadAsBase64(faviconUrl)
          if (base64) return base64
        }
      } catch (error) {
        console.warn('[WebSearch] 获取页面 HTML 失败，回退到 /favicon.ico:', error)
      }

      // 回退到 /favicon.ico
      const fallbackBase64 = await this.downloadAsBase64(`${origin}/favicon.ico`)
      if (fallbackBase64) return fallbackBase64

      return ''
    } catch (error) {
      console.error('[WebSearch] fetchFavicon error:', error)
      return ''
    }
  }

  private normalizeEngine(engine: any): WebSearchEngine {
    const type: WebSearchEngineType = engine?.type === 'webpage' ? 'webpage' : 'search'