重构：CodeMirror 架构优化

核心优化：
- 新增统一导出避免多实例问题
- 语言加载器从动态改为静态导入
- 使用 Compartment 实现主题/语言动态切换

依赖清理：
- 移除废弃的 @codemirror/highlight
- 移除不再使用的 @codemirror/legacy-modes

组件优化：
- CodeEditor 添加内容更新防抖
- 改进亮色主题样式
- 移除不必要的编辑器重建逻辑

构建配置：
- 简化 Vite manualChunks 配置
- 优化依赖预加载列表

文档清理：
- 删除过期的代码审查文档
- 更新版本号 0.3.0 → 0.3.2

web/src/utils/codemirrorExports.js

@@ -0,0 +1,26 @@
+/**
+ * CodeMirror 统一导出
+ * 确保所有模块使用同一个 CodeMirror 实例，避免多实例问题
+ */
+
+// Core
+export { EditorView, lineNumbers, highlightActiveLineGutter, keymap, drawSelection, dropCursor } from '@codemirror/view'
+export { EditorState, Compartment, Facet, StateEffect, StateField } from '@codemirror/state'
+export { defaultKeymap, history, historyKeymap } from '@codemirror/commands'
+export { bracketMatching, defaultHighlightStyle, syntaxHighlighting, StreamLanguage } from '@codemirror/language'
+export { oneDark } from '@codemirror/theme-one-dark'
+
+// Language packages
+export { javascript } from '@codemirror/lang-javascript'
+export { json } from '@codemirror/lang-json'
+export { yaml } from '@codemirror/lang-yaml'
+export { html } from '@codemirror/lang-html'
+export { css } from '@codemirror/lang-css'
+export { cpp } from '@codemirror/lang-cpp'
+export { rust } from '@codemirror/lang-rust'
+export { go } from '@codemirror/lang-go'
+export { python } from '@codemirror/lang-python'
+export { php } from '@codemirror/lang-php'
+export { sql } from '@codemirror/lang-sql'
+export { markdown } from '@codemirror/lang-markdown'
+export { java } from '@codemirror/lang-java'