refactor: 将对话解析器拆分为独立模块

将 lib/conversationParser 重构为 conversation/ 目录:
- 按 API 格式拆分解析器 (claude.ts, openai.ts, gemini.ts)
- 提取公共渲染逻辑到 render.ts
- 添加解析器注册表支持自动格式检测
- 更新组件导入路径

frontend/src/features/usage/components/RequestDetailDrawer/BlockRenderer.vue

@@ -191,7 +191,7 @@
 <script setup lang="ts">
 import { User, Bot, Settings, Wrench, AlertCircle, ChevronRight, FileText, Image as ImageIcon } from 'lucide-vue-next'
 import Badge from '@/components/ui/badge.vue'
-import type { RenderBlock } from '../../lib/conversationParser'
+import type { RenderBlock } from '../../conversation'
 
 defineProps<{
   blocks: RenderBlock[]

frontend/src/features/usage/components/RequestDetailDrawer/ConversationView.vue

@@ -38,7 +38,7 @@
 <script setup lang="ts">
 import { AlertCircle, Zap } from 'lucide-vue-next'
 import BlockRenderer from './BlockRenderer.vue'
-import type { RenderResult } from '../../lib/conversationParser'
+import type { RenderResult } from '../../conversation'
 
 defineProps<{
   renderResult: RenderResult