feat: 预算系统6项技术改进(告警归因/实际值自动归集/真零基/派生规则/告警路径统一/现金流分类)
P1-③ 告警归因: budget_deviation_alerts+alert_type/attribution/scenario_id, 归因引擎alert_attribution.py(子KPI/科目/量价差/趋势), deviation-check统一写归因+场景, GET /deviation-alerts/{id}/attribution详情(旧告警现场组装)
P1-④ 实际值自动归集: kpi_value_sources/kpi_value_collect_logs表+CRUD+试跑+覆盖率, 采集器kpi_value_collector.py(voucher_details/进销存/cash_plans按entity+period汇总, 幂等upsert不覆盖人工), crontab每日06:30
P2-① 真零基: budget_zero_based_items逐项论证表+generate, method-comparison有论证项逐项求和is_demo=false否则fallback
P2-② 派生规则: budget_derivation_rules配置表, apply-method优先读规则rule_source=configured
P2-⑤ 告警双路径合并: deviation_engine.build_deviation_alert统一函数, 方向列表配置化kpi_alert_higher_better+alert-direction接口
P2-⑥ 现金流分类: cash_plan_classify_rules规则表+cash_plan_unclassified待分类队列, sync-cash-plans未命中进队列不静默跳过
新增: GET /kpis/{kpi_id}/values + 前端kpiApi.values(归集标签页数据源), scenario_suggestions幂等seed(init_db)
测试: test_budget_tech_improve.py 15用例, 预算相关96 passed, 全量646 passed