feat: 数据分类分级 — 重要数据标记+资产清单+CSV导出（8/20评估办法政策驱动）

- subjects/kpi_definitions 新增 important_flag/data_level/data_category 列
- 新增 /api/cma/data-classification/* API: inventory/stats/标记/批量/export/industry-reference
- 数据级别: core核心/important重要/general一般（GB/T 43697 简化）
- 前端 DataClassification.vue: 统计概览+清单+打标+导出+行业参考目录
- pytest 17例覆盖（含多租户隔离验证）

frontend/src/router/index.ts

@@ -39,6 +39,7 @@ const routes = [
       { path: 'okr-templates', name: 'OKRTemplates', component: () => import('@/views/OKRTemplates.vue'), meta: { title: 'OKR模板库', roles: ['ceo', 'finance', 'it'], editable: true } },
       { path: 'okr/:id', name: 'OkrDetail', component: () => import('@/views/OkrDetail.vue'), meta: { title: 'OKR详情', roles: ['ceo', 'finance', 'it'] } },
       { path: 'subjects', name: 'SubjectManage', component: () => import('@/views/SubjectManage.vue'), meta: { title: '科目打标', roles: ['ceo', 'finance', 'business', 'it'] } },
+      { path: 'data-classification', name: 'DataClassification', component: () => import('@/views/DataClassification.vue'), meta: { title: '数据分类分级', roles: ['ceo', 'finance', 'business', 'it'], editable: true } },
       { path: 'mpm-calculator', name: 'MpmCalculator', component: () => import('@/views/MpmCalculator.vue'), meta: { title: 'MPM计算器', roles: ['ceo', 'finance', 'business'] } },
       { path: 'bot-kpis', name: 'BotKpis', component: () => import('@/views/BotKpiDashboard.vue'), meta: { title: 'Bot KPI看板', roles: ['ceo', 'finance', 'it'] } },
       { path: 'analysis-confidence', name: 'AnalysisConfidence', component: () => import('@/views/AnalysisConfidence.vue'), meta: { title: '分析置信度', roles: ['ceo', 'finance', 'it'] } },