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

types/index.d.ts

@@ -44,6 +44,10 @@ export interface MarkdownEditorOptions {
   syncScroll?: boolean;
   /** Tab 插入的空格数，0 表示插入 \t，默认 2 */
   tabSize?: number;
+  /** 只读模式，默认 false */
+  readOnly?: boolean;
+  /** 历史栈防抖延迟（ms），默认 400 */
+  historyDebounce?: number;
   /** 主题，默认 'auto' */
   theme?: ThemeName;
   /** 国际化语言，默认 'zh-CN' */
@@ -119,7 +123,8 @@ export interface EditorStatus {
 /** 事件名 */
 export type EditorEventName =
   | 'input' | 'change' | 'focus' | 'blur' | 'save'
-  | 'modeChange' | 'fullscreen' | 'autosave' | 'destroy';
+  | 'modeChange' | 'fullscreen' | 'autosave' | 'destroy'
+  | 'beforeRender' | 'afterRender';
 
 /** 全局钩子名 */
 export type HookName =
@@ -166,6 +171,8 @@ export class MarkdownEditor {
   enable(): this;
   disable(): this;
   isDisabled(): boolean;
+  setReadOnly(readOnly: boolean): this;
+  isReadOnly(): boolean;
 
   // 事件
   on(name: EditorEventName, fn: (...args: any[]) => void): () => void;