fix(cvp): BEP ⑤ 口径统一落地（变动成本率=完整口径）

- 派生器/口径：F_BEP_VC_RATE 新增；卡面/公式行文案改「月固定成本 ÷ 边际贡献率」
- 保本额 = 月固定成本 ÷ (1 − 变动成本率)；实测渠补率(F_BEP_REBATE)降为 e1 专用 chip
- 报告卡口径说明文字同步（固定成本=固定费用合计）

任务: finance-20261003-cvp-fix-and-bohai-coverage-fullstack ⑤

backend/scripts/sql/bep_kpi_defs_20261003_vc_rate.sql

@@ -0,0 +1,39 @@
+-- CMA BEP 变动成本率派生KPI定义 — F_BEP_VC_RATE（2026-10-03 ⑤ 口径统一）
+-- 依据: 任总 2026-10-03 18:00 DM「统一」+ 任务 finance-20261003-cvp-fix-and-bohai-coverage-fullstack §追加⑤
+-- 口径: 变动成本率 = 变动成本 ÷ 收入基数（YTD 累计，2位小数）
+--   · 酣客(e1): 变动成本 = Σ5401借(销货成本)+Σ5403借(税金及附加)+Σ571103借(渠补)−Σ530103贷(厂补)
+--   · 博海(e2): 变动成本 = Σ6401借(主营业务成本)
+--   保本额 = 固定成本月均 ÷ (1 − 变动成本率)
+-- 说明: F_BEP_REBATE(实测渠补率/博海主营成本率) 保留，⑤ 后**不再充当变动成本率**
+-- 幂等: NOT EXISTS 守卫，可安全重跑
+INSERT INTO kpi_definitions
+(entity_id, kpi_code, kpi_name, dimension, category, formula, formula_desc,
+ data_source_type, data_source, data_owner, frequency, unit, target_value,
+ target_calc_type, threshold_green, threshold_yellow, threshold_red,
+ kpi_level, status, bot_source, epic, created_by)
+SELECT 1, 'F_BEP_VC_RATE', '变动成本率', 'finance', 'profitability',
+ 'round((sum(5401借)+sum(5403借)+sum(571103借)-sum(530103贷))/sum(5001贷)*100,2)',
+ '变动成本率(YTD累计,⑤完整口径)=(Σ5401借+Σ5403借+Σ571103借−Σ530103贷)÷Σ5001贷; 供保本点卡面单一事实源; 缺数期不出值(fail-closed)',
+ 'derived', 'BEP派生器 kpi_bep_deriver.py(voucher_details 5401/5403/571103/530103/5001 累计)', '财务部', 'monthly', '%', 0.00,
+ 'ratio', NULL, NULL, NULL,
+ 'strategic', 'active', 'finance-bot', 'Epic2', 1
+FROM DUAL
+WHERE NOT EXISTS (
+  SELECT 1 FROM kpi_definitions WHERE entity_id = 1 AND kpi_code = 'F_BEP_VC_RATE'
+);
+
+INSERT INTO kpi_definitions
+(entity_id, kpi_code, kpi_name, dimension, category, formula, formula_desc,
+ data_source_type, data_source, data_owner, frequency, unit, target_value,
+ target_calc_type, threshold_green, threshold_yellow, threshold_red,
+ kpi_level, status, bot_source, epic, created_by)
+SELECT 2, 'F_BEP_VC_RATE', '变动成本率(主营业务成本率)', 'finance', 'profitability',
+ 'round(sum(6401借)/sum(6001贷)*100,2)',
+ '变动成本率(实测,YTD累计)=Σ6401借方÷Σ6001贷方(剔结转账腿); 博海无渠补科目; 供保本点卡面单一事实源, 无阈值',
+ 'derived', 'BEP派生器 kpi_bep_deriver.py(voucher_details 6401/6001 累计)', '财务部', 'monthly', '%', 0,
+ 'ratio', NULL, NULL, NULL,
+ 'strategic', 'active', 'finance-bot', 'Epic2', 1
+FROM DUAL
+WHERE NOT EXISTS (
+  SELECT 1 FROM kpi_definitions WHERE entity_id = 2 AND kpi_code = 'F_BEP_VC_RATE'
+);