Method update

src/core/nodeviews/code-block.ts:1678–1817

* 更新节点

(node: ProseMirrorNode)

   * 更新节点
   */
  update(node: ProseMirrorNode): boolean {
    if (node.type !== this.node.type) return false;

    const prevLanguage = this.node.attrs.language;
    this.node = node;
    const newText = node.textContent;

    if (newText !== this.cm.state.doc.toString()) {
      this.updating = true;
      this.cm.dispatch({
        changes: {
          from: 0,
          to: this.cm.state.doc.length,
          insert: newText,
        },
      });
      this.updating = false;
    }

    // 更新源码模式下的文本内容
    if (this.sourceViewMode && this.sourceTextElement) {
      const language = node.attrs.language || "";
      const content = node.textContent;
      const fullMarkdown = `\`\`\`${language}\n${content}\n\`\`\``;
      const lines = fullMarkdown.split("\n");

      // 收集当前的文本内容
      const currentLines: string[] = [];
      const childDivs = this.sourceTextElement.querySelectorAll("div.milkup-with-line-number");
      childDivs.forEach((div) => {
        currentLines.push(div.textContent || "");
      });
      const currentText = currentLines.join("\n");

      // 只在内容真正变化时更新
      if (currentText !== fullMarkdown) {
        // 保存光标位置
        const selection = window.getSelection();
        let cursorOffset = 0;
        if (selection && selection.rangeCount > 0) {
          const range = selection.getRangeAt(0);
          if (range.startContainer.nodeType === Node.TEXT_NODE) {
            cursorOffset = range.startOffset;
            // 计算相对于整个文本的偏移量
            let node: Node | null = range.startContainer;
            while (node && node !== this.sourceTextElement && node.previousSibling) {
              node = node.previousSibling;
              cursorOffset += node.textContent?.length || 0;
            }
          }
        }

        this.updating = true;

        // 清空容器并重新创建行
        this.sourceTextElement.innerHTML = "";
        lines.forEach((line) => {
          const lineDiv = document.createElement("div");