feat(S3): content export - Markdown download and PDF print

- Backend: GET /api/export/:type/:id returns .md file download
- Backend: POST /api/export/text for direct text-to-md export
- Frontend: downloadMarkdown() utility for client-side .md download
- Frontend: printAsPdf() utility via browser print dialog
- GenerateView: export dropdown button (MD / PDF) on result card

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vue-app/src/views/GenerateView.vue

@@ -4,6 +4,8 @@ import { useRouter } from 'vue-router'
 import { fetchGenerateMeta, fetchTemplatesByCategory, generatePrompt, continuePrompt } from '@/api/modules/prompt'
 import { quickAddFavorite } from '@/api/modules/favorite'
 import type { PromptTemplateItem } from '@/api/types/template'
+import { ArrowDownBold } from '@element-plus/icons-vue'
+import { downloadMarkdown, printAsPdf } from '@/utils/export'
 
 const metaLoading = ref(true)
 const templatesLoading = ref(false)
@@ -279,6 +281,19 @@ function resetConversation() {
   ElMessage.info('已开始新对话')
 }
 
+function exportMarkdown() {
+  if (!result.value) return
+  const tpl = selectedTemplate.value
+  downloadMarkdown(result.value.generated_text, tpl?.name || '提示词生成结果')
+  ElMessage.success('Markdown 已下载')
+}
+
+function exportPdf() {
+  if (!result.value) return
+  const tpl = selectedTemplate.value
+  printAsPdf(result.value.generated_text, tpl?.name || '提示词生成结果')
+}
+
 async function addToFavorites() {
   if (!result.value || selectedTemplateId.value == null) return
   const tpl = selectedTemplate.value
@@ -439,6 +454,17 @@ onMounted(async () => {
               加入收藏
             </el-button>
             <el-button type="success" plain size="small" @click="copyResult">复制</el-button>
+            <el-dropdown trigger="click" @command="(cmd: string) => cmd === 'md' ? exportMarkdown() : exportPdf()">
+              <el-button type="info" plain size="small">
+                导出 <el-icon class="el-icon--right"><ArrowDownBold /></el-icon>
+              </el-button>
+              <template #dropdown>
+                <el-dropdown-menu>
+                  <el-dropdown-item command="md">Markdown (.md)</el-dropdown-item>
+                  <el-dropdown-item command="pdf">PDF (打印)</el-dropdown-item>
+                </el-dropdown-menu>
+              </template>
+            </el-dropdown>
           </el-space>
         </div>
       </template>