feat: v0.2.3 — 浮动格式工具栏 + 10个新API + 德语翻译 + 类型修复

### Added
- 浮动格式工具栏：选中文本自动弹出 bold/italic/code/link/strikethrough
- 10 个新 API: getSelectedText/getCursorPosition/setCursorPosition/scrollToLine/selectLine/selectAll/replaceAll/replaceAllRegex/lineCount/getLine
- 2 个新事件: selectionChange / cursorMove
- 德语 (de) locale 完整翻译
- floatingToolbar 配置项（默认 true）

### Fixed
- onLinkClick 移除 as any，正式加入 EditorOptions/DEFAULTS
- 所有版本号统一为 0.2.3

### Tests
- core.test.ts: 183 → 214 (+31 tests)
- 总计 ~725 tests

src/index.ts

@@ -1,7 +1,7 @@
 /**
  * MetonaEditor — Type-safe, lightweight Markdown Editor
  * @module metona-editor
- * @version 0.2.1
+ * @version 0.2.3
  */
 
 import { MarkdownEditor } from './core';
@@ -13,7 +13,7 @@ import { animationUtils } from './animations';
 import { DEFAULTS, ICONS, THEMES, EDIT_MODES, DEFAULT_TOOLBAR, TOOLBAR_ACTIONS } from './constants';
 import type { EditMode, ThemeName, ToolbarItem, EditorOptions } from './constants';
 
-const VERSION = '0.2.2';
+const VERSION = '0.2.3';
 
 const globalPlugins: any[] = [];