fix: 复查修复 5 处问题 — URL 双重转义/zen 泄漏/高亮环境不一致等

- parser: href/src/alt 改最小属性转义（escapeAttr 会把已实体化的 &
  再转义成 &，导致链接 URL 双重转义错误）；新增 URL/alt 防回归测试
- core: _pushHistory 增加 maxLength 兜底截断（exec/Tab/Smart Enter/括号
  自动闭合等程序化路径此前绕过 maxlength 限制）
- core: destroy 时清理 Zen 模式的 document mousemove 监听（此前泄漏）
- highlight: 自写环境无关转义（仅 & < >），修复 Node 环境下字符串高亮
  失效、浏览器与 SSR 输出不一致的问题
- floating-toolbar/context-menu: toggleFloatingToolbar/registerContextMenu
  恢复链式 return this（拆分时丢失）
- plugins: 补齐 3 个硬编码文案的 i18n（regex/shortcuts/imageTooLarge），
  6 种语言同步
- 测试 768 → 780

tests/core.test.ts

@@ -2414,3 +2414,79 @@ describe('MarkdownEditor - v0.2.5 分隔条实例隔离', () => {
     a.destroy(); b.destroy();
   });
 });
+
+// ============ v0.2.5 复查：maxLength 兜底 + zen destroy 清理 ============
+
+describe('MarkdownEditor - v0.2.5 maxLength 兜底', () => {
+  test('exec 命令路径不突破 maxLength', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { maxLength: 20, value: '12345678901234567890' });
+    ed.focus();
+    ed.textarea.setSelectionRange(0, 0);
+    ed.exec('indent');
+    expect(ed.getValue().length).toBeLessThanOrEqual(20);
+    ed.destroy();
+  });
+
+  test('Smart Enter 不突破 maxLength', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { maxLength: 30, value: '- item 123456789012345678901234' });
+    ed.focus();
+    ed.textarea.setSelectionRange(ed.getValue().length, ed.getValue().length);
+    ed.textarea.dispatchEvent(new KeyboardEvent('keydown', { key: 'Enter', bubbles: true }));
+    expect(ed.getValue().length).toBeLessThanOrEqual(30);
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.5 zen destroy 清理', () => {
+  test('destroy 移除 zen mousemove 监听', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { zenMode: true });
+    expect(ed._zenMouseHandler).not.toBeNull();
+    const spy = jest.spyOn(document, 'removeEventListener');
+    ed.destroy();
+    expect(spy).toHaveBeenCalledWith('mousemove', expect.any(Function));
+    spy.mockRestore();
+  });
+
+  test('destroy 后 mousemove 不再修改 toolbar', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { zenMode: true });
+    const toolbar = ed.toolbarEl;
+    ed.destroy();
+    toolbar.style.opacity = '1';
+    document.dispatchEvent(new MouseEvent('mousemove', { clientY: 10 }));
+    expect(toolbar.style.opacity).toBe('1');
+  });
+});
+
+// ============ v0.2.5 复查：链式 API 契约 ============
+
+describe('MarkdownEditor - v0.2.5 链式返回', () => {
+  test('toggleFloatingToolbar 返回 this', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, {});
+    expect(ed.toggleFloatingToolbar()).toBe(ed);
+    ed.destroy();
+  });
+
+  test('registerContextMenu 返回 this', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, {});
+    expect(ed.registerContextMenu([{ label: 'x', onClick: () => {} }])).toBe(ed);
+    ed.destroy();
+  });
+});