feat: 报告生成模块（LLM 生成 + PDF 导出 + 前端页面）

- 新增报告生成 API（/api/report/generate, /api/report/export/pdf, /api/report/preview）
- 新增 PDF 导出模块（gofpdf，支持系统中文字体自动检测）
- 新增前端报告生成页面（report/ReportGenerationPage.vue）
- 新增前端 API（report.js）
- 路由注册（后端 router.go + 前端 router/index.js）
- Studio 页面新增「报告生成」应用入口

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

eai_ap_app/frontend/src/router/index.js

@@ -23,6 +23,7 @@ const routes = [
       { path: 'apps/knowledge-operations', name: 'KnowledgeOperationsApp', meta: { workspaceKey: 'knowledge-operations' }, component: () => import('@/views/workbench/BusinessAppPage.vue') },
       { path: 'apps/process-coordination', name: 'ProcessCoordinationApp', meta: { workspaceKey: 'process-coordination' }, component: () => import('@/views/workbench/BusinessAppPage.vue') },
       { path: 'apps/report-generation', name: 'ReportGenerationApp', meta: { workspaceKey: 'report-generation' }, component: () => import('@/views/workbench/BusinessAppPage.vue') },
+      { path: 'report-gen', name: 'ReportGeneration', meta: { requiresAdmin: true }, component: () => import('@/views/report/ReportGenerationPage.vue') },
       { path: 'apps/wechat-official-account', name: 'WechatOfficialAccountApp', meta: { workspaceKey: 'wechat-official-account' }, component: () => import('@/views/workbench/OfficialAccountWorkflowPage.vue') },
       { path: 'apps/logistics-fulfillment', name: 'LogisticsFulfillmentApp', meta: { workspaceKey: 'logistics-fulfillment' }, component: () => import('@/views/workbench/BusinessAppPage.vue') },
       { path: 'apps/hr-email-sorter', name: 'HrEmailSorter', meta: { workspaceKey: 'hr-email-sorter' }, component: () => import('@/views/workbench/BusinessAppPage.vue') },