v0.3.4: Bug修复+性能优化+文档大纲功能

🔴 Bug修复 (6):
- Sidebar反斜杠正则修复 (Windows路径规范化)
- FileWatcher文件删除后自动恢复监听
- SearchReplace replaceAll防过期匹配位置
- openFolderDialog null结果守卫
- 保存异常时空路径保护
- Markdown绝对路径图片拼接修复

🟡 性能优化:
- Editor切换标签时内容比较，相同跳过replaceAll

🔵 代码质量:
- 创建共享常量模块 src/shared/constants.ts，消除双副本

🎯 新增功能:
- 文档大纲 (Table of Contents) — 侧边栏标题导航

🔧 换行符统一: CRLF → LF

src/renderer/stores/editorStore.ts

@@ -1,6 +1,19 @@
 import { create } from 'zustand'
+import type { EditorView } from '@milkdown/prose/view'
 import type { ViewMode } from '../types/settings'
 
+// Module-level getter/setter for the ProseMirror EditorView
+// Used by OutlinePanel for heading navigation
+let _getView: (() => EditorView | null) | null = null
+
+export function setEditorViewGetter(fn: () => EditorView | null) {
+  _getView = fn
+}
+
+export function getEditorView(): EditorView | null {
+  return _getView ? _getView() : null
+}
+
 interface EditorState {
   viewMode: ViewMode
   darkMode: boolean