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）

backend/app/main.py

@@ -5,7 +5,7 @@ from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
 from dotenv import load_dotenv
 from app.database import init_db
-from app.api import auth, kpis, kpi_governance, templates, maps, dashboard, data, alerts, ai_analysis, alert_rules, users, thresholds, notifications, permissions, action_plans, alignment, org, objectives, versions, budget, cost, predict, reports, security, knowledge, bot_bridge, bot_bridge_v2, lead, tenant, customer_dashboard, deviation_push, budget_generate, knowledge_articles, kpi_causality, data_quality, bi_reports, entities, bsc_layers, okr, okr_templates, subjects, driver_budget, bot_kpis, ontology, bot_iron_law, analysis_results, expenses, cash, tax_compliance, verify, growth_quality, products
+from app.api import auth, kpis, kpi_governance, templates, maps, dashboard, data, alerts, ai_analysis, alert_rules, users, thresholds, notifications, permissions, action_plans, alignment, org, objectives, versions, budget, cost, predict, reports, security, knowledge, bot_bridge, bot_bridge_v2, lead, tenant, customer_dashboard, deviation_push, budget_generate, knowledge_articles, kpi_causality, data_quality, bi_reports, entities, bsc_layers, okr, okr_templates, subjects, driver_budget, bot_kpis, ontology, bot_iron_law, analysis_results, expenses, cash, tax_compliance, verify, growth_quality, products, data_classification
 from app.utils.cache import clear_all as clear_cache, delete as delete_cache
 from scripts.erp_sync import run_sync as run_erp_sync
 from app.auth_middleware import require_auth
@@ -80,6 +80,7 @@ app.include_router(bot_iron_law.router)
 app.include_router(analysis_results.router)
 app.include_router(expenses.router)
 app.include_router(cash.router)
+app.include_router(data_classification.router)
 app.include_router(tax_compliance.router)
 app.include_router(verify.router)