feat: v0.2.1 — reference links, context menu, RTL, ja/ko, regex search, hooks, copy API

## Added
- Reference link/image resolution: [text][ref] + ![alt][ref] with [ref]: url definitions
- Right-click context menu: undo/redo/cut/copy/paste/selectAll + custom items
- RTL CSS layout support for Arabic, Hebrew, Persian etc.
- Japanese (ja) and Korean (ko) locales with 60+ keys each
- Divider position localStorage persistence
- Regex search toggle in search/replace panel
- Export HTML with embedded CSS styles
- beforeChange / afterChange lifecycle hooks (instance + global)
- copyAsMarkdown() / copyAsHTML() clipboard APIs
- CHANGELOG.md, CONTRIBUTING.md, CI workflow (.github/workflows/ci.yml)
- 2 new test suites: index.test.ts, styles.test.ts (684 total tests, +74)

## Changed
- autoSave plugin: closure-based state per instance instead of this context
- Plugin install() now receives options as second argument
- RTL locale detection: now uses language prefix (ar-SA → RTL)
- Rollup dev mode: only builds UMD format
- prepublishOnly now includes typecheck + test
- Version bumped to 0.2.1

## Fixed
- [text][ref] now correctly renders as link (was raw text)
- ![alt][ref] no longer produces empty src
- autoSave plugin state isolation across multiple editor instances
- Footnote definitions no longer consumed by refDef handler

tests/core.test.ts

@@ -536,7 +536,7 @@ describe('MarkdownEditor - 构造边界', () => {
       destroy: jest.fn(),
     };
     const ed = new MarkdownEditor(document.createElement('div'), { plugins: [plugin] });
-    expect(plugin.install).toHaveBeenCalledWith(ed);
+    expect(plugin.install).toHaveBeenCalledWith(ed, {});
     ed.destroy();
     expect(plugin.destroy).toHaveBeenCalledWith(ed);
   });
@@ -1731,3 +1731,219 @@ describe('MarkdownEditor - v0.2.0 getStatus plugins', () => {
     ed.destroy();
   });
 });
+
+// ============ v0.2.1 覆盖率补齐测试 ============
+
+describe('MarkdownEditor - v0.2.1 工具栏键盘导航', () => {
+  test('ArrowRight 聚焦下一个按钮', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { toolbar: ['bold', 'italic', 'code'] });
+    const btns = ed.toolbarEl.querySelectorAll('.me-btn');
+    const first = btns[0] as HTMLButtonElement;
+    first.focus();
+    first.dispatchEvent(new KeyboardEvent('keydown', { key: 'ArrowRight', bubbles: true }));
+    // 焦点应移动
+    expect(document.activeElement).not.toBe(first);
+    ed.destroy();
+  });
+
+  test('ArrowLeft 聚焦上一个按钮', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { toolbar: ['bold', 'italic'] });
+    const btns = ed.toolbarEl.querySelectorAll('.me-btn');
+    (btns[1] as HTMLButtonElement).focus();
+    (btns[1] as HTMLButtonElement).dispatchEvent(new KeyboardEvent('keydown', { key: 'ArrowLeft', bubbles: true }));
+    expect(document.activeElement).toBe(btns[0]);
+    ed.destroy();
+  });
+
+  test('Home 聚焦第一个按钮', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { toolbar: ['bold', 'italic', 'code'] });
+    const btns = ed.toolbarEl.querySelectorAll('.me-btn');
+    (btns[2] as HTMLButtonElement).focus();
+    (btns[2] as HTMLButtonElement).dispatchEvent(new KeyboardEvent('keydown', { key: 'Home', bubbles: true }));
+    expect(document.activeElement).toBe(btns[0]);
+    ed.destroy();
+  });
+
+  test('End 聚焦最后一个按钮', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { toolbar: ['bold', 'italic', 'code'] });
+    const btns = ed.toolbarEl.querySelectorAll('.me-btn');
+    (btns[0] as HTMLButtonElement).focus();
+    (btns[0] as HTMLButtonElement).dispatchEvent(new KeyboardEvent('keydown', { key: 'End', bubbles: true }));
+    expect(document.activeElement).toBe(btns[btns.length - 1]);
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.1 ARIA live', () => {
+  test('_initAriaLive 创建 sr-only 元素', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, {});
+    const live = ed.el.querySelector('.me-sr-only');
+    expect(live).not.toBeNull();
+    expect(live!.getAttribute('aria-live')).toBe('polite');
+    ed.destroy();
+  });
+
+  test('_announce 设置消息', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, {});
+    ed._announce('test message');
+    const live = ed.el.querySelector('.me-sr-only') as HTMLElement;
+    expect(live).not.toBeNull();
+    // jsdom 中 requestAnimationFrame 可能不被支持，但不应抛错
+    expect(() => ed._announce('hello')).not.toThrow();
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.1 当前行高亮', () => {
+  test('_updateCurrentLine 高亮当前行', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: 'line1\nline2\nline3', lineNumbers: true });
+    ed.textarea.setSelectionRange(7, 7); // 第二行
+    ed._updateCurrentLine();
+    const active = ed.gutter.querySelector('.me-gutter-active');
+    expect(active).not.toBeNull();
+    ed.destroy();
+  });
+
+  test('_updateCurrentLine 无 gutter 时不抛错', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: 'test', lineNumbers: false });
+    expect(() => ed._updateCurrentLine()).not.toThrow();
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.1 右键上下文菜单', () => {
+  test('contextmenu 事件显示菜单', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: 'hello' });
+    ed.el.dispatchEvent(new MouseEvent('contextmenu', { clientX: 100, clientY: 100, bubbles: true }));
+    const menu = document.querySelector('.me-context-menu');
+    expect(menu).not.toBeNull();
+    // 清理
+    if (menu) menu.remove();
+    ed.destroy();
+  });
+
+  test('上下文菜单点击外部关闭', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: 'hello' });
+    ed.el.dispatchEvent(new MouseEvent('contextmenu', { clientX: 100, clientY: 100, bubbles: true }));
+    expect(document.querySelector('.me-context-menu')).not.toBeNull();
+    document.body.click();
+    // once listener removes it
+    expect(document.querySelector('.me-context-menu')).toBeNull();
+    ed.destroy();
+  });
+
+  test('registerContextMenu 添加自定义菜单项', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, {});
+    ed.registerContextMenu([{ label: 'Custom Action', onClick: jest.fn() }]);
+    expect(ed._contextMenuItems.length).toBe(1);
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.1 copy API', () => {
+  test('copyAsMarkdown 不抛错', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: '# hello' });
+    expect(() => ed.copyAsMarkdown()).not.toThrow();
+    ed.destroy();
+  });
+
+  test('copyAsHTML 不抛错', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: '# hello' });
+    expect(() => ed.copyAsHTML()).not.toThrow();
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.1 beforeChange/afterChange 钩子', () => {
+  test('setValue 触发 beforeChange', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: 'old' });
+    const handler = jest.fn();
+    ed.on('beforeChange', handler);
+    ed.setValue('new');
+    expect(handler).toHaveBeenCalledWith('old', 'new', ed);
+    ed.destroy();
+  });
+
+  test('setValue 触发 afterChange', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { value: 'old' });
+    const handler = jest.fn();
+    ed.on('afterChange', handler);
+    ed.setValue('new');
+    expect(handler).toHaveBeenCalledWith('new', ed);
+    ed.destroy();
+  });
+
+  test('全局 beforeChange/afterChange 钩子', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const beforeFn = jest.fn();
+    const afterFn = jest.fn();
+    MarkdownEditor.on('beforeChange', beforeFn);
+    MarkdownEditor.on('afterChange', afterFn);
+    const ed = new MarkdownEditor(c, { value: 'test' });
+    ed.setValue('updated');
+    expect(beforeFn).toHaveBeenCalled();
+    expect(afterFn).toHaveBeenCalled();
+    MarkdownEditor.off('beforeChange', beforeFn);
+    MarkdownEditor.off('afterChange', afterFn);
+    ed.destroy();
+  });
+});
+
+describe('MarkdownEditor - v0.2.1 分隔条持久化', () => {
+  test('_saveDividerPosition / _restoreDividerPosition 不抛错', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { mode: 'split' });
+    expect(() => ed._saveDividerPosition()).not.toThrow();
+    expect(() => ed._restoreDividerPosition()).not.toThrow();
+    ed.destroy();
+  });
+});