release: v0.1.2 — readOnly, new syntax, plugins, optimizations

Features:
- feat(core): readOnly mode with config option and setReadOnly() API
- feat(parser): superscript ^text^ and subscript ~text~ support
- feat(parser): highlight/mark ==text== syntax
- feat(parser): table column alignment with colons (:---, :---:, ---:)
- feat(parser): emoji shortcodes 😄 → 😊 (80+ common emojis)
- feat(plugins): imagePaste preset — paste clipboard images as base64
- feat(core): instance-level beforeRender/afterRender events
- feat(styles): print stylesheet (@media print)
- feat(styles): mark element CSS styling
- feat(styles): readOnly mode CSS (.me-readonly)

Optimizations:
- perf(core): history debounce now configurable via historyDebounce option
- perf(core): skip _render() in edit-only mode (already guarded)
- fix(core): divider drag division-by-zero guard
- fix(core): config.style deep merge with DEFAULTS
- fix(core): scroll position preserved across mode switches

Tests:
- 9 new test cases: readOnly (3), parser syntax (6)
- Total: 418 tests passing (+9 from v0.1.1)

Chores:
- version bump 0.1.1 → 0.1.2
- TypeScript definitions updated for new APIs

tests/core.test.js

@@ -1241,3 +1241,41 @@ describe('MarkdownEditor - 零散分支补全', () => {
     ed.destroy();
   });
 });
+
+describe('MarkdownEditor - v0.1.2 readOnly 模式', () => {
+  test('config.readOnly 设置 textarea readonly', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { readOnly: true, value: 'locked' });
+    expect(ed.textarea.readOnly).toBe(true);
+    expect(ed.el.classList.contains('me-readonly')).toBe(true);
+    ed.destroy();
+  });
+
+  test('setReadOnly 动态切换', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, {});
+    expect(ed.isReadOnly()).toBe(false);
+    ed.setReadOnly(true);
+    expect(ed.isReadOnly()).toBe(true);
+    expect(ed.textarea.readOnly).toBe(true);
+    expect(ed.el.classList.contains('me-readonly')).toBe(true);
+    ed.setReadOnly(false);
+    expect(ed.isReadOnly()).toBe(false);
+    expect(ed.textarea.readOnly).toBe(false);
+    expect(ed.el.classList.contains('me-readonly')).toBe(false);
+    ed.destroy();
+  });
+
+  test('readOnly 模式下内容仍可读取', () => {
+    document.body.innerHTML = '';
+    const c = document.createElement('div');
+    document.body.appendChild(c);
+    const ed = new MarkdownEditor(c, { readOnly: true, value: '# hello' });
+    expect(ed.getValue()).toBe('# hello');
+    ed.destroy();
+  });
+});