feat: 添加文稿版本管理、差异对比高亮和多项功能优化

- 修复AI重写输出过滤（过滤thinking/draft标签）
- 添加文稿保存与版本管理功能
- 新增插入差异功能（差异对比模式）
- 实现版本历史侧边抽屉（DocumentVersionPanel）
- 添加版本对比差异高亮显示
- 调整文稿编辑区高度适应屏幕
- 新增MarkdownEditor组件（暂未启用）

src/App.vue

@@ -8,18 +8,32 @@
       <!-- 左侧面板 -->
       <WriterPanel v-if="currentPage === 'writer'" />
       <AnalysisPanel v-else-if="currentPage === 'analysis'" />
-      <DocumentsPanel v-else-if="currentPage === 'documents'" />
+      <DocumentsPanel 
+        v-else-if="currentPage === 'documents'" 
+        @toggle-version-panel="toggleVersionPanel"
+        @document-selected="handleDocumentSelected"
+      />
       <MaterialsPanel v-else-if="currentPage === 'materials'" />
       <SettingsPanel v-else-if="currentPage === 'settings'" />
       
       <!-- 右侧主内容区 -->
       <MainContent />
+      
+      <!-- 版本历史面板（仅文稿管理页面显示） -->
+      <DocumentVersionPanel 
+        v-if="currentPage === 'documents'"
+        :visible="showVersionPanel"
+        :document-id="selectedDocumentId"
+        :current-content="selectedDocumentContent"
+        @close="showVersionPanel = false"
+        @restore="handleVersionRestore"
+      />
     </template>
   </div>
 </template>
 
 <script setup>
-import { computed } from 'vue'
+import { ref, computed } from 'vue'
 import { useAppStore } from './stores/app'
 import WriterPanel from './components/WriterPanel.vue'
 import AnalysisPanel from './components/AnalysisPanel.vue'
@@ -28,7 +42,33 @@ import MaterialsPanel from './components/MaterialsPanel.vue'
 import SettingsPanel from './components/SettingsPanel.vue'
 import MainContent from './components/MainContent.vue'
 import ComparePanel from './components/ComparePanel.vue'
+import DocumentVersionPanel from './components/DocumentVersionPanel.vue'
 
 const appStore = useAppStore()
 const currentPage = computed(() => appStore.currentPage)
+
+// 版本历史面板状态
+const showVersionPanel = ref(false)
+const selectedDocumentId = ref(null)
+const selectedDocumentContent = ref('')
+
+// 切换版本面板
+const toggleVersionPanel = () => {
+  showVersionPanel.value = !showVersionPanel.value
+}
+
+// 处理文稿选择
+const handleDocumentSelected = (doc) => {
+  selectedDocumentId.value = doc?.id || null
+  selectedDocumentContent.value = doc?.content || ''
+}
+
+// 处理版本恢复
+const handleVersionRestore = (content) => {
+  selectedDocumentContent.value = content
+  // 刷新 MainContent 显示
+  if (appStore.currentDocument) {
+    appStore.currentDocument.content = content
+  }
+}
 </script>