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/parser.test.ts

@@ -1118,3 +1118,110 @@ describe('parseMarkdown - 分支：嵌套列表子项渲染', () => {
     expect(innerUlCount).toBeGreaterThanOrEqual(2);
   });
 });
+
+// ============ v0.2.1 引用链接/图片测试 ============
+
+describe('parseMarkdown - v0.2.1 引用链接', () => {
+  test('引用链接 [text][ref] 解析为链接', () => {
+    const md = 'Click [here][1]\n\n[1]: https://example.com';
+    const html = parseMarkdown(md);
+    expect(html).toContain('<a href="https://example.com"');
+    expect(html).toContain('>here</a>');
+  });
+
+  test('引用链接忽略大小写', () => {
+    const md = 'Visit [Site][MyRef]\n\n[myref]: https://example.com';
+    const html = parseMarkdown(md);
+    expect(html).toContain('<a href="https://example.com"');
+  });
+
+  test('引用链接无定义时保留原文', () => {
+    const md = 'Click [here][undef]';
+    const html = parseMarkdown(md);
+    expect(html).not.toContain('<a href=');
+    expect(html).toContain('here');
+  });
+
+  test('引用链接使用隐式引用（同文本）', () => {
+    const md = 'Visit [example][]\n\n[example]: https://example.com';
+    const html = parseMarkdown(md);
+    expect(html).toContain('<a href="https://example.com"');
+  });
+
+  test('引用图片 ![alt][ref] 解析', () => {
+    const md = '![logo][img1]\n\n[img1]: https://example.com/logo.png';
+    const html = parseMarkdown(md);
+    expect(html).toContain('<img src="https://example.com/logo.png"');
+    expect(html).toContain('alt="logo"');
+  });
+
+  test('引用图片带 title 通过 parseMarkdown', () => {
+    clearRenderCache();
+    const md = '![logo][img1]\n\n[img1]: https://example.com/logo.png "MyLogo"';
+    const html = parseMarkdown(md);
+    expect(html).toContain('src="https://example.com/logo.png"');
+    expect(html).toContain('title="MyLogo"');
+  });
+
+  test('引用链接带 title 通过 parseMarkdown', () => {
+    clearRenderCache();
+    const md = '[link][1]\n\n[1]: https://example.com "MyTitle"';
+    const html = parseMarkdown(md);
+    expect(html).toContain('href="https://example.com"');
+    expect(html).toContain('title="MyTitle"');
+  });
+
+  test('引用链接危险协议被过滤', () => {
+    const md = 'Click [bad][1]\n\n[1]: javascript:alert(1)';
+    const html = parseMarkdown(md);
+    expect(html).not.toContain('href="javascript:');
+  });
+
+  test('引用图片无定义时使用空 src', () => {
+    const md = '![logo][nope]';
+    const html = parseMarkdown(md);
+    expect(html).toContain('src=""');
+    expect(html).toContain('me-img-ref');
+  });
+
+  test('引用定义不匹配脚注', () => {
+    const md = 'Text[^1]\n\n[^1]: footnote text\n\n[link][lnk]\n\n[lnk]: https://example.com';
+    const html = parseMarkdown(md);
+    expect(html).toContain('me-footnotes');
+    expect(html).toContain('footnote text');
+    expect(html).toContain('<a href="https://example.com"');
+  });
+});
+
+// ============ v0.2.1 data:image 超限测试 ============
+
+describe('parseMarkdown - v0.2.1 safeUrl 增强', () => {
+  test('超长 data:image URL 被过滤', () => {
+    // 构造一个超过 500000 字符的 data:image URL
+    const longData = 'data:image/png;base64,' + 'A'.repeat(500001);
+    const url = safeUrl(longData);
+    expect(url).toBe('');
+  });
+
+  test('正常 data:image 通过', () => {
+    const url = safeUrl('data:image/png;base64,abc123');
+    expect(url).toBe('data:image/png;base64,abc123');
+  });
+});
+
+// ============ v0.2.1 引用链接格式错误容错 ============
+
+describe('parseMarkdown - v0.2.1 引用链接容错', () => {
+  test('格式错误的引用图片不崩溃', () => {
+    const html = parseMarkdown('![broken ref');
+    expect(html).toContain('broken ref');
+  });
+
+  test('引用定义中 JSON 解析错误被容错', () => {
+    // 正常情况下 refs 中的值是 JSON 字符串
+    const { refs } = parseTokens('[link][test]\n\n[test]: https://example.com');
+    expect(refs['test']).toBeDefined();
+    // 不应抛错
+    expect(() => renderTokens([{ type: 'paragraph', text: '[x][bad]' }], { refs: { bad: 'not-json' } })).not.toThrow();
+  });
+});